Difference between revisions of "Diving the Cape Peninsula and False Bay"
Revision as of 23:58, 6 January 2012
This article is a travel topic
This regional dive guide is intended to provide the already qualified Scuba diver with information which will help to plan dives in the waters of the Cape Peninsula and False Bay, whether as a local resident or a visitor. Information is provided without prejudice, and is not guaranteed accurate or complete. Use it at your own risk.
The region described is within a day trip from any part of greater Cape Town, in the Western Cape province of South Africa and includes well over 100 dive sites, which is a large number for any single destination.
Detailed information on individual dive sites is provided in the sub-articles linked from the Dive sites section. The information in the site descriptions ranges from superficial to highly detailed, depending on what is known about the site.
In some instances a dive site sub-article will include several sites which are in close proximity, as much of the information will be common to them all. In other cases, usually involving wreck sites, two closely adjacent sites will each have their own sub-article, but if two or more wrecks lie in the same position, or with substantioal overlap, they will both be described in the same sub-article.
The City of Cape Town was founded at the northern end of the Cape Peninsula, a narrow mountainous strip of land at the most 30km wide and just over 100km long. The northern border is the coast of Table Bay, a large open bay with a single island, Robben Island, in its mouth.
A ragged coastline marks the western border along the Atlantic ocean. A number of small bays are found along the coast with a single large one, Hout Bay, about half way along. Further south the peninsula narrows until it comes to an end at Cape Point. A range of mountains with Table Mountain at 1085m at the northern end forms the backbone of the peninsula. The highest point of the southern peninsula is Swartkop, at 678m, near Simon’s Town.
The eastern side is bordered by False Bay, and this stretch of coastline includes the smaller Smitswinkel Bay, Simon’s Bay and Fish Hoek Bay. At Muizenberg the coastline becomes relatively low and sandy and curves east to Gordon’s Bay to form the northern boundary of False Bay. From Gordon's Bay the coastline swings roughly south, and zig-zags its way along the foot of the Hottentot’s Holland mountain range to Cape Hangklip which is at nearly the same latitude as Cape Point. The highest peak on this side is Kogelberg at 1269m.
In plan the bay is approximately square with rather wobbly edges, being roughly the same extent from north to south as east to west (30km), with the entire southern side open to the ocean. The area of False Bay has been measured at about 1090km2, and the volume is approximately 45km3 (average depth about 40m). The land perimeter has been measured at 116km, from a 1:50 000 map.
The bottom morphology of False Bay is generally smooth and fairly shallow, sloping gently downwards from North to South, so that the depth at the centre of the mouth is about 80m. The bottom is covered with sediment which ranges from very coarse to very fine, with most of the fine sediment and mud in the centre of the bay. The main exception is a long ridge of sedimentary rock that extends in a southward direction from off the Strand, to approximately level with the mouth of the Steenbras River. The southern tip of this ridge is known as Steenbras Deep.
There is one true island in the bay, Seal Island, a barren and stony outcrop of granite about 200m long and with an area of about 2 hectare. It is about 6km south of Strandfontein and is less than 10m above sea level at its highest point. There are also a number of small rocky islets which extend above the high water mark, and other rocks and shoals which approach the surface. Most of these are granite of the Peninsula pluton, but east of Seal Island they are generally sandstone, probably of the Table Mountain series, though it is possible that some may be of the underlying Tygerberg formation.
Outside the bay, but influencing the wave patterns in it, is Rocky Bank, an extensive area of sandstone reef between 20 and 30m depth.
Strictly speaking, False Bay is part of the Atlantic ocean which extends as far as Cape Agulhas, but when in Cape Town, Atlantic generally refers to the western seaboard of the Cape Peninsula, and the east side is referred to as False Bay, or the Simon's Town side. This convention will be used throughout this guide.
Climate, weather and sea conditions
Climate of the Western Cape
The climate of the South-western Cape is markedly different from the rest of South Africa, which is a summer rainfall region, receiving most of its rainfall during the summer months of December to February. The South-western Cape has a Mediterranean type climate, with most of its rainfall during the winter months from June to September.
During the summer the dominant factor determining the weather in the region is a high pressure zone, known as the Atlantic High, located over the South Atlantic ocean to the west of the Cape coast. Winds circulating in an anticlockwise direction from such a system reach the Cape from the south-east, producing periods of up to several days of high winds and clear skies. These south easterly winds are locally known as the Cape Doctor. They keep the region relatively cool and help to blow polluted air from the industrial areas and Cape Flats out to sea. Because of its south facing aspect False Bay is exposed to these winds, particularly on the west side, while Table Bay and the west coast of the peninsula experience an offshore wind. This wind pattern is locally influenced by the topography to the extent that gale force winds may be blowing in Gordon’s Bay, while about 10km away parts of Somerset West may have a sweltering and windless day.
Winter in the South-western Cape is characterised by disturbances in the circumpolar westerly winds, resulting in a series of eastward moving depressions. These bring cool cloudy weather and rain from the north west. The south westerly winds over the South Atlantic produce the prevailing south-westerly swell typical of the winter months, which beat on the exposed Atlantic coastline and the east side of False Bay. The mountains of the Cape Peninsula provide protection within the west side of False Bay from this wind and from the south westerly waves – a fact which influenced Governor Simon van der Stel in his choice of Simon’s Bay as a winter anchorage for the Dutch East India Company’s ships for Cape Town. The north westerly winter storms have wrecked many ships anchored in Table Bay over the centuries. Even today, in spite of technical advances and improved weather forecasting this still happens, though less frequently than in the past, and these days the salvage operations are more often successful.
There can be considerable variation in weather conditions between different sites in the area covered by this guide on any day, though the general tendency may be similar. For example rain may fall on the Cape Peninsula in the morning, and by afternoon these conditions may have moved over to the east side of False Bay and the peninsula may be clearing with a significant wind directional shift from north westerly to south westerly. The general trend is for the weather to come in from the west and move eastwards with the frontal systems, but there can also be more local weather phenomena such as thunderstorms (rare) and Berg winds, which are warm winds coming down off the mountains. Local variation in wind strength may be extreme, and sometimes hard to believe, as there may be a dead calm in one place and a howling wind a few kilometres away. There are places known for exposure to both south easterly and north westerly winds, and some which are sheltered from one or the other, while the south-westerlies blow most places, but not usually to quite the same extremes. What this amounts to in practice, is that the weather conditions where you are at a particular time may differ significantly from those at a dive site a bit later in the day.
Waves and swell
The waves reaching the shores of False Bay and the Cape Peninsula can be considered as a combination of local wind waves and swell from distant sources. The swell is produced by weather systems generally south of the continent, sometimes considerably distant, the most important of which are the frontal systems in the South Atlantic, which generate wind waves which then disperse away from their source and separate over time into zones of varying period. The long period waves are faster and have more energy, and move ahead of the shorter period components, so they tend to reach the coast first. This is known to surfers as a pulse, and is generally followed by gradually shortening period swell of less power.
Local winds will also produce waves which will combine their effects with the swell. Offshore winds as a general rule will flatten the sea as the fetch (distance that the wind has blown over the water) is too small to develop waves of great height or length. Onshore winds on the other hand, if strong enough will produce a short and nasty chop which can make entry and exit uncomfortable, and surface swims or boat rides unpleasant.
The combination of swell and wind waves must be considered when planning a dive. This requires knowledge of these conditions, which are forecast with variable accuracy by a number of organisations, in some cases up to 7 days ahead.
South-easterly winds which blow offshore and along the coast on the west side of the Cape Peninsula and the east side of False Bay cause a movement of surface water northwards along the coast and offshore to the west of the coast. This movement of water away from the coast is compensated by the upwelling of deeper water.
These upwellings are of considerable interest to the diver, as the upwelled water is generally cold and relatively clear. However, as the upwelled water has a high nutrient content, the upwellings are often forerunners of a plankton bloom known as a "red tide", which will drastically reduce visibility.
On the east side of False Bay the upwellings often cause poor visibility as they can disturb the very fine and low density sediment which is common on that side of the bay, particularly in the shallower part near Gordon's Bay. The water is also relatively cold, but not usually as cold as on the west side of the peninsula and temperatures may drop from around 19°C to 12°C over a day or two.
The local tides are relatively weak, and there are no strong tidal currents on the Atlantic coast or in False Bay. The resulting tidal flows are of little consequence to the diver, the main effect being slight changes in the depth at the dive site and variations on the obstacle presented by kelp fronds near the surface, which can affect the effort required to get through the kelp at the surface. In this regard it is generally easier at high tide.
Boat launches at some slipways can be difficult at low tide, which can occasionally affect boat dive schedules.
Maximum tidal range at Cape Town is approximately 1.86m (spring tides), and at Simon’s Town 1.91m, with minimum ranges at both places of about 0.26m (neap tides).
Average summer surface temperature of the Atlantic off the Cape Peninsula is in the range 10° to 13°C. The bottom temperature may be a few degrees colder. Minimum temperature is about 8°C and maximum about 17°C. Average winter surface temperature of the Atlantic off the Cape Peninsula is in the range 13° to 15°C. The bottom temperature inshore is much the same.
Average winter surface temperature of False Bay is approximately 15°C, and the bottom temperature much the same. Average summer surface temperature of False Bay is approximately 19°C. The bottom temperature is 1° to 3°C lower than it is in winter.
Currents are not usually considered an issue at most dive sites in this region. A shallow surface current may be produced by strong winds, which can be an inconvenience if it sets offshore. This surface layer is shallow and a diver may return to shore at 3m depth below the current. Tidal currents are negligible, and are only experienced at a few isolated dive sites, such as Windmill, during spring tides when there is some swell running.
The only two places which may experience significant currents are at the mouth of False Bay, at Rocky Bank and Bellows Rock, where eddies from the Agulhas current frequently produce a light- to medium-strength current, which may be strong enough to inconvenience divers in the shallows around Bellows Rock.
Predicting the weather and sea conditions
Predicting diving conditions in this region is fairly complex. There are websites such as Buoyweather , Surf-Forecast  and Windguru  which provide reasonably reliable forecasts for wind and swell. This combined with information on recent conditions of water temperature and visibility will allow a fairly reliable prediction of conditions a few days in advance. The local Wavescape  website and surf report is also a valuable reference with a distinctive South African ambience, though like the others, it is primarily intended for surfers, and divers must interpolate a bit.
Visibility can clear up quite quickly (overnight) on the Atlantic coast due to currents and relatively coarse sediments. On the west side of False Bay it is a little slower, and it can take several days, even weeks, on the east side of the bay, where the sediments are fine and light.
Until you have developed a feel for this procedure, it is useful to get second opinions from people or organisations with experience. Some of the local dive charter operators have better reputations for weather prediction than others, and there are some who will almost always claim that conditions are or were good. The Blue Flash  weekly newsletter is as good as any other and better than many.
The marine ecology
Cape Point at the tip of the Cape Peninsula is considered the boundary between two of the five inshore marine bioregions of South Africa. To the west of Cape Point is the cool to cold temperate South-western Cape inshore bioregion, and to the east is the warmer temperate Agulhas inshore bioregion. The Cape Point break is considered to be a relatively distinct change in the bioregions and this can be clearly seen from the difference in marine life between the Atlantic seaboard of the peninsula and False Bay.
Four major habitats exist in the sea in this region, distinguished by the nature of the substrate. The substrate, or base material, is important in that it provides a base to which an organism can anchor itself, which is vitally important for those organisms which need to stay in one particular kind of place. Rocky shores and reefs provide a firm fixed substrate for the attachment of plants and animals. Some of these may have Kelp forests, which reduce the effect of waves and provide food and shelter for an extended range of organisms. Sandy beaches and bottoms are a relatively unstable substrate and cannot anchor kelp or many of the other benthic organisms. Finally there is open water, above the substrate and clear of the kelp forest, where the organisms must drift or swim. Mixed habitats are also frequently found, which are a combination of those mentioned above. The habitats are described in more detail in the following sections.
Rocky shores and reefs
The great majority of popular dive sites in the local waters are on rocky reefs or mixed rocky and sandy bottoms, with a significant number of wrecks, which are equivalent to rocky reefs for classification of habitat, as in general, marine organisms are not particular about the material of the substrate if the texture and strength is suitable and it is not toxic. For many marine organisms the substrate is another type of marine organism, and it is common for several layers to co-exist. Examples of this are red bait pods, which are usually encrusted with sponges, ascidians, bryozoans, anemones, and gastropods, and abalone, which are usually covered by similar seaweeds to those found on the surrounding rocks, usually with a variety of other organisms living on the seaweeds.
The type of rock of the reef is of some importance, as it influences the range of possibilities for the local topography, which in turn influences the range of habitats provided, and therefore the diversity of inhabitants.
Granite reefs generally have a relatively smooth surface in the centimetre to decimetre scale, but are often high profile in the metre scale, so they provide macro-variations in habitat from relatively horizontal upper surface, near vertical sides, to overhangs, holes and tunnels, on a similar scale to the boulders and outcrops themselves. There are relatively few small crevices compared to the overall surface area.
Sandstone and other sedimentary rocks erode and weather very differently, and depending on the direction of dip and strike, and steepness of the dip, may produce reefs which are relatively flat to very high profile and full of small crevices. These features may be at varying angles to the shoreline and wave fronts. There are far fewer small caverns and swimthroughs in sandstone reefs, but often many deep but low near-horizontal crevices. In some areas the reef is predominantly wave-rounded medium to small boulders. In this case the type of rock is of little importance.
The coastline in this region was considerably lower during the most recent ice-ages, and the detail topography of the dive sites was largely formed during the period of exposure above sea level. As a result, the dive sites are mostly very similar in character to the nearest landscape above sea level.
There are notable exceptions where the rock above and below the water is of a different type. These are mostly in False Bay south of Smitswinkel Bay, where there is a sandstone shore with granite reefs.
Kelp forests are a variation of rocky reefs, as the kelp requires a fairly strong and stable substrate which can withstand the loads of repeated waves dragging on the kelp plants. The Sea bamboo Ecklonia maxima grows in water which is shallow enough to allow it to reach to the surface with its gas-filled stipes, so that the fronds form a dense layer just below the surface. The shorter Split-fan kelp Laminaria pallida grows mostly on deeper reefs, where there is not so much competition from the sea bamboo. Both these kelp species provide food and shelter for a variety of other organisms, and particularly the Sea bamboo, which is a base for a wide range of epiphytes, which in turn provide food and shelter for more organisms.
The Bladder kelp Macrocysta angustifolia can also be found at a few sites, mostly near Robben Island. This is one of the few places in the world where three genera of kelps may be found at the same place.
Sandy beaches and bottoms (including shelly, pebble and gravel bottoms)
Sandy bottoms at first glance appear to be fairly barren areas, as they lack the stability to support many of the spectacular reef based species, and the variety of large organisms is relatively low. The sand is continually being moved around by wave action, to a greater or lesser degree depending on weather conditions and exposure of the area. This means that sessile organisms must be specifically adapted to areas of relatively loose substrate to thrive in them, and the variety of species found on a sandy or gravel bottom will depend on all these factors.
For these reasons sandy and gravel bottoms are not usually popular with novices and visitors, who are usually attracted to the more spectacular sites, but to the diver who is interested in the full variety of the marine environment they can provide a refreshing and fascinating variation, as there are a lot of organisms which will only be found on these bottom types. Mostly they can be found adjacent to reef areas, but there are a few sites which are predominantly sandy.
Sandy bottoms have one important compensation for their instability, animals can burrow into the sand and move up and down within its layers, which can provide feeding opportunities and protection from predation. Other species can dig themselves holes in which to shelter, or may feed by filtering water drawn through the tunnel, or by extending body parts adapted to this function into the water above the sand.
On the west coast of the peninsula and to a lesser extent the east side of False Bay, the south easterly winds can cause upwelling of deep, cold, nutrient rich waters. This generally happens in summer when these winds are strongest, and this in combination with the intense summer sunlight provides conditions conducive to rapid growth of phytoplankton. If the upwelling is then followed by a period of light wind or onshore winds, some species of phytoplankton can bloom so densely that they colour the water, most noticeably a reddish or brownish colour, which is known as a red tide.
Depending on the species involved, these red tides may cause mass mortalities to marine animals for various reasons. In some cases the organisms may consume all the available nutrients and then die, leaving decaying remains which deplete the water of oxygen, asphyxiating the animal life, while others may simply become so dense that they clog the gills of marine animals, with similar effect. A third group are inherently toxic, and these may be particularly problematic as some filter feeding species are immune to the toxins but accumulate them in their tissues and will then be toxic to humans who may eat them.
Red tides also have the more direct effect on diving conditions of reducing visibility. The reduction in visibility can range from a mild effect in the surface layers, to seriously reduced visibility to considerable depth.
Red tides may be small and localised and usually last for a few days, but in extreme cases have been known to extend from Doringbaai to Cape Agulhas, several hundred kilometres to both sides of Cape Town, and take weeks to disperse (March 2005).
Most of the dive sites in this region are relatively shallow and can be done on air with ordinary recreational diving equipment, which would include:
To this you can add:
For each dive site there may be additional or alternative equipment required or recommended, which may improve the dive experience or improve safety at that site. The most commonly recommended items are:
Use of a compass is recommended wherever it may be desirable to swim back to shore below the surface to avoid wind or boat traffic, or to keep below the kelp fronds. It is required for the compass navigation routes.
A dry suit is recommended for most dives on the Atlantic seaboard, or in general if the dive is deeper than about 20m and the water is colder than 13°C. An appropriate undergarment is required for the dry suit, at this is what provides the insulation. With a suitable combination it is possible to enjoy an hour's dive in comfort at a water temperature of 8°C, when most of the divers in 7mm wetsuits are cold after 30 minutes. If your face and head are particularly sensitive to cold, a full-face mask will keep your face warm.
Recommendations for a light are for daytime dives, as lights are considered standard equipment on night dives. Backup lights should be carried on night dives from a boat. Underwater flashers may not be well received by the other divers as they are extremely annoying. If you feel you must use one, warn the others and stay away from those divers who do not wish to have a light continually flashing in their peripheral vision and distracting them. A strobe which may be switched on in an emergency is another matter entirely, and is accepted as a valuable safety aid.
The equipment recommendations are for divers who are competent to use those items, and if you are not, you should consider whether your competence is sufficient to dive the site without this equipment.
No recommendations are made regarding equipment for wreck penetration dives and deep dives. If you do not know exactly what equipment is required and have it with you, or are not competent in its use, you should not do the penetration. Depth, wrecks and caves are nature’s tools for culling reckless divers.
Recommendations for gas mixtures are generic. You must choose the appropriate mixture based on your qualifications, competence and the dive plan. Nitrox mixtures are generally recommended to increase dive time without obligatory decompression stops, and Trimix to reduce narcotic effects. Nitrox is available from many of the dive shops, and charter operators will usually provide cylinders filled with the blend of your choice if given sufficient notice. Trimix is more difficult to arrange, as not many filling stations keep Helium in stock, so it may require a bit of shopping around.
Decompression dives should generally only be planned by divers who are familiar with the site, and are competent and properly equipped for the planned dive. Recommendations in this regard are outside the scope of this article, and it will be necessary to discuss any planned decompession dives well in advance with the dive operator, as only a few of them are competent and willing to support planned decompression dives, and those will usually require strong evidence of your competence to do the dive, and advance notice of your dive plan.
Diving equipment other than open circuit back mounted Scuba with half mask and mouth-grip demand valve is considered to be exotic for this section. This would include surface supplied breathing apparatus and full face masks, used as standard equipment by commercial divers, and rebreathers, seldom used by commercial divers, but frequently used by military divers and gaining popularity with Technical recreational divers. Also considered as exotic equipment is side-mount Scuba and diver propulsion vehicles (scooters), as they are not used by many recreational divers.
Generally speaking, any use of surface supplied diving equipment will require special preparation and logistics, which are not available from the listed service providers, but are perfectly legal for use and technical support is available from the suppliers to the commercial diving industry in Cape Town.
Rebreathers are relatively uncommon, but are used by a few local afficionados, and sorb is available over the counter at a few suppliers. There is even one charter boat which regularly runs dives for mainly rebreather divers. Expect to be checked out for skills and certification before being allowed to join these dives, so it would be advisable to make prior arrangements. Technical support is available for a limited range and parts will usually only be available from overseas agencies. Most of the local dive sites do not really justify the expense and relative risk of rebreathers, and they are mostly used by divers who also use them in other places where they are more of an advantage, and by those who just enjoy the technology.
Full-face masks will not be a problem, provided you can show your ability to provide buddy support if diving with a partner (some charters will insist that you dive with a buddy). Technical support and parts are available from local agencies for most of the more popular models used for commercial and technical diving, but you may have to wait some time if parts are not in stock. The use of a full-face mask can be a particular advantage when the water is cold, and if you have one and prefer to use it, by all means bring it to Cape Town.
Side mount Scuba is virtually unknown in Cape Town, but there should be no problems if you chose to use it. Do not expect boat crews to know how to help you kit up, but they will probably respond well to explanations.
Diver propulsion vehicles (scooters) are rare but not unknown. Check with the charter boat whether will be space on board for your unit, and don't expect to find one for rental.
The dive sites described in these articles include some which are well known favorites and have been dived frequently and by many divers for decades, and also newly described sites, which may only have been dived a few times, and by a few divers. There are also sites which have been known for years, but seldom dived due to their relative inaccessibility, and a few which are basically not particularly interesting, but have been included in the interests of completeness, as the information is available, and occasionally people want to know what they are like. With a few exceptions, the information provided is based on personal observation at the sites by Wikitravellers. All photos of marine life and features of interest were taken at the listed site.
Geographical information is provided in as much detail as currently available. Sites are geolinked, which allows them to be identified on various internet map systems. Positional accuracy is usually good. The maps provided should be usable, to scale, and accurate, but are not guaranteed either to be correct in all details or complete. Clicking on the thumbnail will open a link to a higher resolution image.
Atlantic coast of the Cape Peninsula:
Introduction and some tips on diving the Atlantic coast.
This coastline from Table Bay to Cape Point is exposed to the south westerly swells generated by the cold fronts of the Southern Ocean. The continental shelf is narrow in this part of the coast and swells are not greatly influenced by the narrow band of shallow water, so they retain most of their deep-water energy. These swells pound this coast most of the winter, and to a lesser extent in summer, so diving in this region is mostly a summer activity, and the frontal weather patterns far to the south are more important than local weather for swell prediction.
The south easterly winds are offshore in this area and tend to blow the swell down a bit. They also cause an offshore displacement of the surface water, which results in deeper water rising to take its place. This upwelling brings colder, initially cleaner water to the inshore areas, and can produce conditions of 20m+ visibility and temperatures down to 8°C, though more usually 10° to 12°C. The diving is wonderful if you are sufficiently insulated. Out of the water, however, it is commonly fine and hot, with blazing sunshine and air temperatures in the high 20°C’s and 30°C’s. This means you will be overheating until you get in the water, hence the comment that summer diving in Cape Town is one easy step from hyperthermia to hypothermia.
There is no escaping the need for a well-fitting, thick (preferably 7mm), wet suit or a dry suit with an adequate undergarment for these conditions if you intend to stay for more than a few minutes. Carrying a bottle of water with your equipment to wet the outside of your suit before or after putting it on will help keep the temperature down due to evaporative cooling, specially on a windy day. Overheating after leaving the water is seldom a problem. The alternative option of kitting up at the water’s edge requires a shore party to look after your clothes etc. while you dive, so it has become less common recently. Do not leave equipment unattended if you wish to see it again.
An upwelling is frequently followed by a plankton bloom, often called a red tide. This will reduce visibility considerably, particularly near the surface. Often the water will be much clearer below the surface layer, though the light levels may be a bit dim and the colour relatively green.
The south-easter is an offshore wind, and besides its influence on temperature and visibility, it also affects the swim back to shore after the dive. The south-easter can appear seemingly out of nowhere on a previously cloudless and windless day, and build up to near gale force in the time you are underwater on a dive, though it is usually predictable, so take note of weather forecasts, and in any case, allow sufficient reserve air to swim back a few metres below the surface. A compass is extremely useful if you do this as it allows you to swim shallower, which is good for air consumption, decompression and warmth. A depth of 3 to 5m is recommended for a long swim home. The strong south-easter in these cases produces a short, steep wind chop with white-caps which does not penetrate to any significant depth, but the constant slapping of waves and the spray in the air can make snorkelling unpleasant and difficult. There may also be a shallow offshore wind drift (surface current), but this does not usually extend below about a metre depth inshore.
When boat diving a deployable surface marker buoy is useful to both facilitate controlled ascent and accurate decompression or safety stop depth, and as a signal to the boat that you are on your way up. In strong wind conditions it will also improve your visibility on the surface, specially if your equipment is all black, so it is worth carrying even if only as a signalling device. Bright yellow has been shown to be best for all round visibility at sea, but orange and red are fairly good too.
These sites are all boat dives. There is no other practical way to get to them, as they are all several kilometres from the mainland across major shipping lanes.
Local Geography: Robben Island is a low, rocky shored island in the mouth of Table Bay. The island and surrounding reefs are rock of the Tygerberg series of the late Precambrian Malmesbury group. These are folded sedimentary rocks, frequently with very steep dip, which often weather to form rather jagged outcrops.
The sites include:
Local Geography: There is a narrow coastal plain at the base of Signal Hill and Lion’s Head. The contact zone between the intrusive granites of the Peninsula pluton and the sedimentary greywackes and shales of the Tygerberg formation of the Malmesbury series is in this area. The northern sites are on the Tygerberg rocks, which are steeply dipped and form parallel ridges and gullies, while Bantry Bay is on the granite, and has the characteristic corestone topography of rounded boulders and outcrops with sand bottom in deeper areas.
The sites include:
Clifton Rocks is generally considered a shore dive, but the Paws are quite a distance offshore and are only dived from boats. Parking in Clifton is often a problem, particularly in the kind of weather in which you may wish to go diving. Weekdays will be better and early morning will help. The offshore dives avoid this problem by using boats from Oceana Power Boat Club slipway, which has its own parking problems, though not quite as serious.
Local Geography: The suburb of Clifton is built on the rather steep slopes of the base of Lion’s Head above Clifton Bay. There are four beaches in the bay which are famous for white sand, shelter from the south easter and cold water. North Paw is offshore of the headland to the north, and South Paw is offshore from Clifton Rocks, on the south headland. Access to the area by road is from Sea Point to the north and Camps Bay to the south.
The reefs of Clifton are granite corestones of the Peninsula pluton. In this area the granite base of the mountain extends to approximately the height of Signal Hill, and is capped by sandstones of the Graafwater and Table Mountain formations. Occasional rounded granite outcrops can be seen on the mountainside, which is mostly deeply weathered granitic saprolite, with some sandstone scree.
The sites include:
Local Geography: Camps Bay is in the corner made by Lion’s Head and Table Mountain. Access is over Kloof Nek from the city bowl, and round the coast from Sea Point via Clifton to the north, and from Hout Bay via Oudekraal to the south
The reefs of this area are like those of Clifton.
The sites include:
This area includes some of the best and most popular shore dive sites on the Atlantic seaboard. Most can also be dived from a boat, and this is of particular importance to divers with restricted mobility on shore, as there is generally a rugged bit of coast to negotiate and in some cases a long climb. There is also a moderate to long swim at some of the sites, and at some states of the tide, heavy kelp inshore.
Local Geography: The coastline at the base of the Twelve Apostles range just south of Table Mountain is steep, and south of Camps Bay, virtually undeveloped. Fortunately for divers, the coastal road is not far above sea level in the north of this area, and though there are not many off-road parking areas, the road is wide enough to park along the side.
This is an area of pale grey Peninsula Granite corestone outcrops and boulders with some Table Mountain Sandstone boulders which have rolled down the mountainside to the water’s edge. The mountainside below the sandstone cliffs is deeply weathered granite saprolite with occasional corestone outcrops. The cuttings at the roadside display the granular yellow-brown saprolite with a thin soil covering. The underwater topography is almost entirely corestones exposed by erosion, surrounded by samd, and is a continuation of the granite boulders and outcrops at the water’s edge.
The sites include:
The sites include:
The sites include:
These sites can be accessed from the shore or by boat. Parking is limited, but the area is reasonably secure. Some walking is required, but no serious climbing as the parking is near the sea level.
Local Geography: The small residential suburb of Llandudno is built on the moderately steep slopes of the Cape Peninsula below the peak of Klein-Leeukop, where the coast road (M6 – Victoria Drive) from Camps Bay crosses over the neck to Hout Bay. There is only one way into Llandudno by road, which is from the M6 near the top of the pass. This is an area of granite corestone reefs with sand bottom.
The sites include:
Leeugat (Maori Bay)
Although several of the sites are quite close inshore, this area is in practice only accessible by boat, as the distance to the nearest parking is too far to carry dive gear (about 3km as the crow flies, more on foot).
Local Geography: Leeugat, also known to divers as Maori Bay, lies at the foot of the Karbonkelberg, between the northern headland of Oude Schip, and Duikerpunt to the south. It is a small bay, but fairly deep close inshore, which in combination with the partial barrier afforded by the reefs at the headlands, has provided the wrecks in Leeugat bay with better protection from wave action than those on more exposed parts of the coastline. This means that not only have they lasted well for their ages, but conditions are suitable for diving more often than for many other wrecks on the Atlantic seaboard of the Cape Peninsula.
This is an area of granite bedrock of the Peninsula pluton, The reefs are exposed corestone outcrops and boulders, with sand patches in the deeper areas
The sites include:
Outer Hout Bay
This area includes the dive sites between Duiker Point and Duiker Island and the extensive reefs to the south as far as Vulcan Rock and Tafelberg Reef. All of these are only accessible by boat. There are a number of sites being explored in this area: the reefs between Kanobi’s wall and Stonehenge, and a wreck of a lifeboat which was used to salvage materials from the Boss 400 and which lies between Stonehenge and Duiker Island are amongst these. There are several unexplored pinnacles in the region identified on the SAN charts as bakleiplaas, where the sea is often very lumpy due to the influence of the underwater topography on the swell.
Local Geography: The suburb of Hout Bay lies in the valley between the Constantiaberg to the east and the peninsula formed by Karbonkelberg and its lesser peaks to the west. One of these peaks, the Sentinel, gives its name to a dive site at its foot. At the mouth of the valley is the business area of Hout Bay, with its small commercial fishing harbour and marina, and a public slipway used by dive charters and private dive boats for access to most of the southern peninsula dive sites on the Atlantic coast. The slipway is in good condition, wide and accessible, and has a large parking area, which on occasions can be crowded due to heavy use by commercial fishing skiboats.
The bedrock of this area is granite of the Peninsula pluton, and most of the sites are on corestone reefs of this rock.
The sites include:
This area includes the sites between the Sentinel and Chapmans Peak. Most of these are boat dives. The one exception, Sentinel, can be accessed by land without great difficulty, but has a security problem.
The Sentinel is a typical area of granite coastline, with large numbers of boulders along the shore and corestone reefs with the usual rounded profiles.The wrecks of the Aster and Katsu Maru are on a flat sand bottom, and the site at Die Josie is on relatively unweathered granite at the base of the cliffs of Lower Chapman’s Peak
The sites include:
This area includes all of the peninsula coast south of Noordhoek. It is not often dived for recreational purposes as it is a long way from good launch sites and not many good dive sites are known. There are several wrecks in this area, particularly at Albatross Rocks/Olifantsbospunt. Only a few of the wrecks have been positively identified.
The sites include
False Bay coast of the Cape Peninsula:
Introduction and some tips on diving the False Bay coast of the Cape Peninsula (Simon’s Town side)
Unlike the rest of the region, the west side of False Bay is sheltered from the winter westerlies, but in return it takes the South-easter head on. As a result of this the region is usually dived in winter, when the South-easter seldom blows for long or with great force.
The winter frontal storms over the Southern Ocean produce swells which are slowed by the continental shelf and refracted and diffused round the Cape Peninsula, so that they propagate mostly parallel to the coastline, and have lost much of their energy by the time they curve in towards the shore. The irregular form of the coast here also protects some areas more than others. Generally speaking, those parts of the coast which run in a more north west to south east direction are better protected from the south west swell than the north to south parts, so the choice of dive site is dependent on the recent weather patterns.
During the summer months when the South-easter blows more frequently, for longer, and generally harder, this area is not often diveable, and the visibility is generally poorer than in winter even when conditions are otherwise suitable.
The water temperature during the winter months in this area is generally warmer than the Atlantic coast in summer, which is some compensation for the shorter daylight hours and often cold and rainy weather.
Between the cold and rainy fronts there are frequently days of little or no wind, and mild to warm sunshine, when the water is flat and clear and the diving is wonderful, and the large number of sites easily accessible from the shore make it difficult to decide where to go as there is so much choice. It’s a tough life here at the end of Africa, but somebody has to do it.
Water temperature during winter is usually between 13°C and 17°C, though it has been known to drop as low as 11°C, so a good suit is also needed here. In summer the temperature may rise above 20°C, but is more likely to be around 17°C to 19°C.
Most of the shore dives are relatively shallow, in the order of 8m to 15m maximum depth, though it is possible to do a 30m shore dive if you don’t mind a 700m swim to get there. The shallow waters make a dry suit less advantageous, but getting out of a wet suit in the wind and rain at night push the dry suit up again as a desirable option. It is nice to have the choice, and many local divers interchange wet and dry suits depending on the dive planned.
These sites are the northernmost sites of the west side of False Bay. They are shallow and exposed to the south easterly winds and waves, so are generally considered winter dives.
Local Geography: There is a narrow strip of land between the mountainside and the sea which is occupied by the suburbs of St James and Kalk Bay, and at the southern end of this there is a small hill called Trappieskop. At this point the coastline curves out into False Bay before turning back to form Fish Hoek Bay. The small commercial fishing harbour at Kalk Bay is built in this cove.
This is an area where the shoreline is sandstone of the Table Mountain series, and the dip is nearly horizontal at about 7° to the south. The resulting shoreline is generally rocky, with some sandy areas, and is surprisingly shallow considering the steepness of the mountainside. Sand bottom starts at about 5m depth at Dale Brook and nearer 9m at the harbour.
The sites include:
Fish Hoek and Glencairn
These relatively shallow sites are exposed to south easterly wind and swell and are generally considered winter dives. All can be done as shore dives, though Fish Hoek Reef and Quarry Barge are usually done as boat dives as there is a long swim from shore. Great White sharks have been seen cruising in this area.
Local Geography: The low lying and relatively flat valley of Fish Hoek is bounded on the south side by the steep slopes of Brakkloofrant and Else Peak, which also slopes steeply to the sea on the east.
Fish Hoek Reef is some distance off the beach, and the other dive sites of this area are along this short stretch of rocky coastline. The main road to Simon’s Town, the M4, and the railway line share the narrow coastal strip. There is space for a few houses at Sunny Cove, and just past Quarry the Else river has cut a smaller valley with Glencairn beach. The quarry referred to is a disused sandstone quarry on the mountainside above the road just to the north of the dive site of that name.
This is an area where faulting has caused the Table Mountain Sandstones to extend below sea level, The strike is generally east-west and the dip is shallow, from about 7° (south) at Sunny cove to about 10° (south) at Quarry. Jointing however is approximately north west/south east.
The sites include:
The small bay on the eastern side of the Cape Peninsula known as Simon’s Bay is the most sheltered part of the False Bay coastline from the south westerly swells, and is also better protected from south easterly swells than any other place on this part of the coast. As the main anchorage of the Cape at Table Bay is badly exposed to the north westerly storms of winter, and Hout Bay is open to the south westerly swells, Simon’s Bay was the only reasonably safe alternative anchorage within a reasonable distance from Cape Town, and for these reasons was chosen by the first Dutch Governor at the Cape, Simon van der Stel, as the winter anchorage for the Dutch East India Company at the Cape.
The town that developed at this anchorage became known as Simon’s Town, and the anchorage developed into the headquarters and dockyard for the Southern hemisphere of the Royal Navy and later for the South African Navy, which it remains to this day.
The overland access to the town is relatively poor, comprising the winding and narrow main road along the False Bay coast, with the parallel Boyes Drive and railway line, the even more winding Chapman’s Peak drive on the Atlantic coast, and the Old Cape Road (Ou Kaapseweg), a fairly steep and winding pass over the mountains in the middle of the peninsula. All are scenic routes, but none are really suited to high volume traffic, and can be annoyingly congested during rush hour. All converge on the False Bay coastal road just before reaching Simon’s Town.
The dive sites are fairly sheltered from south east wind and swell, more so further south at Long Beach, and are diveable most of the winter and some of the time in summer.
Local Geography: The town is at the base of the coastal mountains, which are quite steep and have very little reasonably flat ground at the foot of the slopes, however the bay is shallow and mostly sandy bottomed, with a long sandy beach on the western side. To the east of the Naval dockyard the coastline becomes rocky again, with exposed granite corestones at Seaforth.
This area has a sandstone coastline, probably Graafwater series, but not much reef is exposed at the dive sites which are mostly on sand bottom.
The sites include:
Roman Rock reefs
The offshore dives in the vicinity of Roman Rock are relatively exposed to the south east swells, but are deeper, so the effect is less severe once you are at depth. Strong south east wind and chop can make the boat trip uncomfortable, so these sites are not often dived in summer, when the visibility is frequently poor.
Local Geography: The sea bed is mostly very gradually sloping sand in this area, with massive granite outcrops, which are the dive sites. The sand tends to be fairly fine away from the reefs, with coarser shelly sand near the base of the rocks.
The offshore sites at Roman Rock, Rambler Rock and Castor Rock are huge granite corestones of the Peninsula pluton.
The sites include:
Seaforth to Froggy Pond
These sites are to the east and south of the Naval dockyard at Simon's Town. They are moderately shallow and exposed to the south east wind and swells, so are generally considered winter dives.
Local Geography: These sites are all areas of granite corestone reef, though there may be occasional sandstone boulders.
The sites include:
Oatlands Point is the first point south of the Froggy Pond area. There is a small group of houses on the seaward side of the main road, and more houses up the mountainside. It is easily recognised by the large flattish topped granite boulder just offshore.
Local Geography: Oatlands Point is at the foot of Swartkop peak, at 678m, the highest point of the southern peninsula. The mountainside is fairly steep, and the houses are in a fairly narrow band along the coast. This is the part of False Bay where the 30m isobath is at its closest point to the shore and where access is good for a shore dive.
These sites are all areas of granite corestone reef, though there may be occasional sandstone boulders. The smaller boulders along the shore are often sandstone which have moved down the mountainside over the years and have been rounded in the surf.
The sites include:
South of Oatlands Point, the shore gets steeper, and there are not many houses. The road winds along the shoreline, gaining altitude slightly towards Miller’s Point. Rocklands Point is recognisable from the road by Spaniard Rock. a moderately large sized granite rock about 100m offshore, and the largest visible rock in the area.
The shore is rather steep at Rocklands Point, and there are no houses in the immediate vicinity. There is an extensive area of shallow rocky reef inshore of Rocklands blinder and Spaniard Rock. South of Spaniard Rock, and extending to a blinder to the south known as Stern Reef, is an area of scattered granite reef, mostly low, but with a few fairly high outcrops. This area is complex and has not yet been mapped.
Like the sites to the north and south, this is an area of granite corestones on a sand bottom, though sandstone boulders are frequently found at the water’s edge.
The sites include:
Local Geography: This part of the peninsula coastline is a steep mountainside below the Swartkopberge. The mountainside is quite steep close to the shore, but on reaching the sea, the slope flattens out dramatically. The small rocky peninsula of Miller’s Point juts out rather abruptly into the bay and provides a sheltered site for the slipway from which most of the boat launches in this area are made. There is sufficient reasonably level ground for extensive parking areas off the main road, including boat trailer parking.
This area is characterised by large areas of granite corestone reef interspersed with with sandy patches, and relatively flat sand bottom further out. There are also sandstone boulders along the shoreline. Many of the reefs are fairly large areas of massive outcrops with ridges, gullies and boulders on top, some of which are very large.
The sites include:
This has been a marine sanctuary area for many years and as a result is one of the best sites for fish. There are several excellent dive sites accessible from a very limited amount of roadside parking, or by a short boat ride from Miller's Point.
Local Geography: This part of the peninsula coastline is a steep mountainside below the Swartkopberge. There is very little ground along this strip which is not steep, but on reaching the sea, the slope flattens out and the small rocky peninsula of Castle Rocks juts out into the bay. There is sufficient reasonably sloped ground for a few houses above and below the main road.
This area is characterised by granite corestone reefs with sandy patches between them, and almost flat sand bottom further out. There will occasionally be the odd sandstone boulder which has made its way a short distance offshore with the assistance of wave action and gravity, and a lot of the smaller shoreline boulders are sandstone. Many of the reefs are fairly large areas of massive ridges, gullies with occasional loose boulders on top, and some of these boulders are huge.
The sites include:
Partridge Point area
The stretch of coastline south of Castle Rocks to Smitswinkel Bay is not really accessible from the road, partly due to the higher altitude of the road in this area and partly due to the rather steep mountainside, so these dive sites, though mostly close to the shore, are almost always dived from a boat.
Local Geography: There are two small points along this relatively straight coastline at Finlay’s Point and Partridge Point, where some very large granite corestones form reefs which extend some distance into the bay. A few of these project quite high above the water and are easy landmarks for the dive sites.
The shoreline is consistently rocky in this section, and is made up of granite corestones with sandstone boulders which have found their way down the mountainside over the years. Above the waterline, the lower mountainside is granitic saprolith with dense vegetation cover.
The wrecks of Smitswinkel bay are among the best known and most popular boat dives of the Cape Town area. The water is deep enough to reduce surge significantly and shallow enough for recreational divers. The wrecks are easy to find, large and sufficiently intact to be recognisable, and have also developed a thriving ecology which includes a few relatively rare organisms.
Local Geography: Smitswinkel Bay is a moderately large bay on the east side of the Cape Peninsula. The coast road gains altitude as it winds along the mountainside south of Simon’s Town and turns inland at Smitswinkel Bay.
To the north of the bay, the exposed rock at sea level is Peninsula granite, but on the south side the Graafwater sandstone extends below sea level. The bottom of the bay is flat sand.
The sites include:
A small group of dive sites just to the south of Smitswinkel Bay. They are inaccessible by land due to the steep cliffs along the shore and lack of nearby roads.
Local Geography: These sites are at the foot of Judas Peak, the mountain peak on the south headland of Smitswinkel Bay. Their position at the base of the steep cliffs gives them protection from south westerly winds and swell, but they will catch some of the north westerly wind which comes through the gap above Smitswinkel Bay. They are exposed to south easterly winds and waves.
The shoreline and shallow reef at Smits Cliff is Table Mountain Sandstone, probably Graafwater series, while the offshore reefs at Smits Reef and Batsata Rock are Peninsula Granite. The unconformity is near sea level in this area.
The sites include:
This site is inside the Cape Point National Park area. Access is controlled by the Parks Board and various fees are charged. A slipway at Buffels Bay is also controlled by Parks Board, and the facilities are usually in good condition, It would probably be more popular if access was allowed after 6pm.
Local Geography: Buffels Bay is the closest place to Cape Point where there is road access to a place sufficiently sheltered for a slipway to be viable.
The shoreline is sandstone in this area.
The sites include:
False Bay Offshore
Introduction and some tips on diving the Central False Bay sites.
All the sites in this area are fairly far offshore, and can only be done as boat dives. They are also relatively deep and because of the long boat trip and exposed positions, generally only dived when conditions are expected to be good.
This area is exposed to the same south westerly swells as the Atlantic coast, but they must travel over a much wider continental shelf, much of which is less than 100m deep, so there is a significant dissipation of wave energy before it reaches the shoreline.
During summer the strong south easterly winds have sufficient fetch to produce sea states which are unpleasant and though the wave action may not produce a great deal of surge at the bottom, the surface conditions may be unsuitable for diving, and in winter the north wester can have a similar effect.
As the area is affected by the winds and wave systems of both winter and summer, there is less seasonal correlation to suitable conditions, and it is simply dived when conditions are good, which is not very often.
It is quite common for the surface visibility offshore to be poor, with better visibility at depth, but the reverse effect can also occur. These effects are often associated with a thermocline. Water temperature can differ with depth from 20°C on the surface to 9°C at the bottom at 28m, sometimes with a distinct thermocline, though usually there is less of a change. A dry suit is recommended for any of these dives, but they are also often done in wetsuits.
These sites are not dived as frequently as the inshore reefs, as they are further from the launch sites and therefore take considerably longer to get to. They are also more exposed to the weather from all directions, so the trip is often bumpy. However, as they are relatively deep, and far offshore, the visibility can be very good, and may well be better than inshore areas at any given time, particularly with an onshore wind and swell. Unfortunately this is not reliably predictable.
Local Geography: The topography of the reefs differs according to the geology of the area. As a result the character varies enormously.
Seal Island and Whittle Rock are granite outcrops, probably all part of the Cape Peninsula pluton. Steenbras Reef is sedimentary rock, thought to be Tygerberg formation of the Malmesbury series, but looks more like sandstone than shale, and Rocky Bank is sandstone, probably of the Table Mountain group.
The sites include:
There are a number of wrecks in central False Bay. Only the ones that are identified and dived are listed here. Exploration of previously undived wrecks occurs sporadically and the list is sure to increase over time. These wrecks are relatively deep, and are all too far offshore to dive from the shore. Some of them are considered among the best dive sites of the Cape Town area, at least partly because of the difficult access and rarity value.
Local Geography: The "Lusitania" is on a site where the granite reef is ruggedly spectacular and the boat trip provides a magnificent view of Cape Point. The "General Botha", "Bloemfontein" and "Fleur" are on the flat sand bottom of the bay and in these cases, only the wreck is of much interest.
The sites include:
Eastern False Bay coast
Introduction and some tips on diving the Eastern False Bay coast from Gordon’s Bay to Hangklip.
This coast is exposed to the same south westerly swells as the Atlantic coast, but they must travel over a much wider continental shelf, much of which is less than 100m deep, so there is a significant dissipation of wave energy before it reaches the shoreline. There are other influences, as some of the swells must pass over the shoal area known as Rocky Bank in the mouth of False Bay, and this tends to refract and focus the wave fronts on certain parts of the shore, depending on the exact direction of the wave fronts. As a result there is a tendency for some parts of the coast to be subjected to a type of “freak wave” which appears to be a combination of focused wave front, superposition sets and the effects of the local coastal topography. There are a number of memorial crosses along the coast to attest to the danger of these waves, though the victims are generally anglers, as divers would not attempt to dive in the conditions that produce these waves.
This area, like the Atlantic coast, is a summer diving area, though there will occasionally be conditions suitable for a winter dive. Even in milder conditions there tend to be more noticeable sets than on the Atlantic coast, and it is prudent to study the conditions for several minutes when deciding on an entry or exit point, as the cycle can change significantly over that time. Timing is important at most of these sites, and often when returning to the shore it may seem that the conditions have deteriorated dangerously during the dive. If this happens, do not be in a rush to exit, hang back for at least one cycle of sets, and time your exit to coincide with the low energy part of the cycle, when the waves are lowest and the surge least. When you exit in these conditions, do not linger in the surge zone, get out fast, even if it requires crawling up the rocks on hands and knees, and generally avoid narrow tapering gullies, as they concentrate the wave energy.
The local geology has produced a coastline with much fewer sheltered exit points on this side of the bay, adding to the difficulty, but there are a few deep gullies sufficiently angled to the wave fronts to provide good entry and exit points in moderate conditions. The most notable of these is at Percy’s Hole, where an unusual combination of very sudden decrease in depth from about 14m to about 4m, a long, narrow gully with a rocky beach at the end, and a side gully near to the mouth which is shallow, wide, parallel to the shoreline, and full of kelp, results in one of the best protected exits on the local coastline. As a contrast, Coral Garden at Rooi-els, which is about 1.7 km away, has a gully that shelves moderately, with a wide mouth and very small side gullies, which are very tricky unless the swell is quite low.
There is no significant current in False Bay, and this results in relatively warmer water than the Atlantic coast, but also there is less removal of dirty water, so the visibility tends to be poorer. The south easter is an offshore wind here too, and will cause upwelling in the same way as on the Atlantic coast, but the bottom water is usually not as clean or as cold, and the upwelled water may carry the fine light silt which tends to deposit in this area when conditions are quiet, so the effects are usually less noticeable. These upwellings are more prevalent in the Rooi-els area, which is deeper than Gordon’s Bay.
As in the Atlantic, a plankton bloom frequently follows an upwelling. This will reduce the visibility, particularly near the surface. It is quite common for the surface visibility offshore to be poor, with better visibility at depth, but the reverse effect can also occur, particularly inshore. These effects are often associated with a thermocline.
Surface water temperature on this side of the bay can range from as high as 22°C to as low as 10°C, and the temperature can differ with depth, sometimes with a distinct thermocline.
This area includes some of the best and most popular shore dive sites in the east side of False Bay. All can also be dived from a boat, and this is of particular importance to divers with restricted mobility on shore, as there is generally a rugged bit of coast to negotiate and in some cases a long climb. There are also sites which are only dived from boats as the shore access is too difficult or dangerous. The dive sites are all close inshore, as sand bottom is quite close to the shore in most cases, There is little or no kelp at these sites.
Local Geography: The coastline from Gordon’s Bay to just north of Steenbras River mouth lies approximately north east to south west along the foot of the Hottentot’s Holland mountain range. This is a steeply sloping area with low cliffs along the shoreline and no level ground. The southern part of the Gordon’s Bay urban area is perched along the northern end of this strip above the Faure Marine Drive (R44), which is the access road for all shore dives in this area except Bikini Beach.
The dive sites from Bikini Beach to Lorry Bay are along this part of the coast, and are more sheltered from south westerly swell than sites further to the south as a result of the orientation of the coastline approximately parallel to the swell direction.
Further south the coastline curves to the south east, so the sites are more exposed to the swell. By Rocky Bay the swell approaches the coastline almost perpendicularly, which makes it relatively rough in any south westerly swell.
The shoreline topography of this area is generally low rocky cliffs with occasional wave-cut caves, gullies and overhangs. The underwater profile is usually quite steep with the flat sand bottom quite close to the shoreline. Maximum depth increases from north to south, reaching just over 20m at Rocky Bay, where the rocky bottom extends much further out than at the more northerly sites.
The coastal formation in this area is mostly light grey to yellow brown quartzitic sandstones of the Graafwater formation. This directly overlays the greywackes of the Malmesbury group which form the coastline further north from Gordon’s Bay to the Strand. Higher up the mountainside are the rocks of the Peninsula formation, which are light grey quartzitic sandstone, with thin siltstone, shale and conglomerate beds. The strike is roughly parallel to the coastline, approximately ENE, and the dip is steep SSW, nearly vertical in places.
The sites include:
This area includes some of the best and most popular shore dive sites in the east side of False Bay. All can also be dived from a boat, though there is limited access for launching in the area, and it is a long ride from Gordon’s Bay. At many of these sites there is a rugged bit of coast to negotiate and in some cases a long climb. The dive sites are mostly close inshore, but in some cases extend out a considerable distance. There is usually kelp in the shallower areas at these sites. Baboons can be a nuisance at Rooi-els, though here they are not quite as problematic as south of Simon’s Town. Do not leave unattended food open, and do not feed the baboons as this encourages then to become even more of a nuisance.
Local Geography: The sites to the north of Rooi-els Bay are at the foot of Rooielsberg (636m), which slopes rather steeply on the north west side, but has a more gradual slope just to the north of the Rooi-els river mouth, where there is a sandy beach well sheltered from the south west swells. However, the underwater topography is in apparent contradiction to this, as the site at Bloukrans is shallower and more gradually shelving than at Percy’s Hole, where the depth drops off to about 12m within a very short distance of the shoreline.
Outcrops of dark rock of the Tygerberg formation at Bloukrans, with sandstones of the Table Mountain series further south. Strike is about north east at Rooi-els, with dip around 25° south east.
The sites include:
Pringle Bay and Hangklip
These areas are mostly dived by spearfishers, but are known to have been dived on scuba. Unfortunately no information is available at this stage.
The sites include:
Fresh water dive sites
There is only one fresh water site of note in the region which is open to the public. This is the Blue Rock Quarry at the bottom of Sir Lowry’s Pass, near Gordon’s Bay,
The sites include:
Diving on rocky reefs
As a general rule avoid contact with living organisms. This is obviously impossible in Kelp forests, so it is fortunate that sea bamboo and the split-fan kelp are both fast growing and tough. In fact it is recommended that if you need to steady yourself in a surge, you use the lower part of the kelp stipes as handholds in preference to other organisms if there is no clear substrate to grip. They are generally strongly attached to the substrate as they must withstand a severe battering in storms, so the occasional diver holding on seems a light burden. In some cases small kelp plants may be ripped off in strong surge. You will learn to recognise when this is likely to happen and must then make another plan.
The damage done by divers in our local marine ecology appears to be mostly to slow-growing relatively fragile organisms below the surf zone. The false corals (Bryozoa) appear to be among the more fragile, and all contact with the scrolled, pore-plated and staghorn false corals should be avoided. Hard corals, soft corals, anemones and sea fans should also be treated as very sensitive. Sponges are probably less sensitive to being touched, but are not generally very strong and can tear fairly easily, and are unsuitable for holding on.
Red bait (the very common and prolific large sea squirt Pyura stolonifera) seems to be tough and resilient, and can be used as handholds, as it seems to take no noticeable harm, This does not apply to all ascidians, most are much more delicate. Red bait is also frequently the substrate for other, more delicate organisms, in which case, treat with the care appropriate to the more delicate species.
Kicking the reef and stirring up the sand bottom with your fins is considered bad form and the mark of an unskilled diver. Avoid this by maintaining neutral buoyancy and being aware of your position relative to your surroundings, keep leg and arm movements moderate, trim yourself to allow appropriate body orientation, and avoid dangling equipment, which may bang into the reef or get hooked up on things and cause direct or indirect damage. As a general rule, a horizontal orientation with fins raised above the torso is appropriate and allows maneuvering by using the fins without kicking the reef or stirring up a cloud of sand.
Some photographers seem to have developed a nasty habit of shifting things around to suit the desired composition of the picture. This is extremely irresponsible and should not be done, as the handling may be fatal to some organisms. It is also illegal in Marine Protected Areas, though in practice, virtually impossible to enforce.
Collection of marine organisms is illegal without the appropriate permit. If you need the organisms for some legitimate purpose, get the permit. Otherwise leave them undisturbed, and do not unnecessarily disturb other neighbouring organisms if you do collect.
There are concerns regarding the impact of sport diving on the reef ecology. Some of these may be legitimate, and study is necessary to test whether this is a real problem. The number of dives in the region has increased significantly over the years, but there is no numerical data available. The number of sites has also increased, so the frequency of dives at most sites will not have increased proportionately. Unfortunately the government department of Marine and Coastal Management has seen an opportunity to interfere with sporting activity and has made use of surveys on tropical coral reefs to support an effort to take control of sport diving on the temperate reefs around the Cape Peninsula. No surveys of temperate reefs can be produced to justify their claims and it seems unlikely that their interference will benefit either the ecology or the diving industry.
Marine Protected Areas
A large number of the dive sites of Cape Town are in the Table Mountain National Park Marine Protected Area as published in the Government Gazette No. 26431 of 4th June 2004 in terms of the Marine Natural Resources Act, 18 of 1998.
A permit is required to scuba dive in any MPA. The permits are valid for a year and are available at some branches of the Post Office. Temporary permits, valid for a month, may be available at dive shops or from dive boat operators.
Boundaries of this Marine Protected Area are shown in the image, which also shows the Restricted zones, where in theory, no fishing or harvesting activities are allowed. This does not stop the poachers, and if you have political pull it appears that you can get commercial fishing permits for some of the restricted zones.
Wreck diving around the Cape Peninsula and False Bay
Diving on wrecks in South Africa is a popular activity, and historical wrecks are legally protected against vandalism and unauthorised salvage and extractive archaeology. An interesting, though not particularly logical consequence of the legislation, is that any wreck automatically becomes a historical wreck 60 years after the date of wrecking, with the effect that a pile of rusty rubbish, which anyone can remove at will, can overnight become a valuable and irreplaceable historical artifact and part of the National Heritage. There seems to be a similar effect on divers, who will assiduously scrabble around in a wreck, in the hope of finding an artifact that they wouldn't bend over to pick up if it lay in the street.
Nevertheless, wreck diving has its attractions, and the waters of the Cape Peninsula and False Bay have a large number of wrecks. The reasons for this are firstly that one of the world's major shipping routes passes round Cape Point, and secondly that the weather and sea conditions in this region can be very rough. The anchorage in Table Bay provides little shelter if the wind is from the north west, which is common in winter, and many ships have been driven ashore in and near Table Bay during winter storms when anchors have dragged or cables failed, and the ship was unable to beat off the lee shore. This happens less frequently since ships were motorised, but every few years another ship is blown ashore in Table Bay due to breakdowns or incompetence.
The list of wrecks is long, but the list of wrecks in areas convenient for diving is much shorter, and a significant number of the wrecks that are probably in convenient areas, have not been found. — Recording an exact position as the vessel went down was not often a high priority to the crews, even when it would have been possible. As a result, there is continued exploration and searches made by the wreck diving enthusiasts for wrecks for which approximate positions are known, and there are a few operators who jealously guard their knowledge of wreck locations so that they can have exclusive access.
Many ships sank a significant distance beyond the point at which they were damaged, and many in water either too deep to dive or right up on the shore, where they were subsequently battered to bits by wave action. Others have deteriorated to the point where the average recreational diver would hardly recognise them as the remains of a ship. As a result of these factors, the number of wrecks which are popular dive sites is a small subset of the total number known, and many of these were originally scuttled, either as naval target practice, or as artificial reefs. These wrecks are dived fairly frequently, as conditions allow.
In case of emergency:
For diving emergencies where there may be a requirement for recompression, the National Hyperbarics chamber is on 24 hour standby, but the personnel may not be at the facility all the time. In cases where there is a need for life support during evacuation, contact one of the paramedic services such as Netcare 911. If the diver is a DAN member, at least try to contact DAN (Diver Alert Network) during the evacuation, as they will make further arrangements. For non-DAN members contact the paramedic service or Metro Rescue direct.
If you need to transport the casualty yourself, go to the Claremont Hospital Emergency Medical Unit first, where the personnel know about diving accidents and can provide life support and appropriate treatment until the chamber is ready. Transport from Claremont Hospital to National Hyperbarics is just across a parking lot.
It is strongly recommended that someone from the dive group should accompany the casualty in the ambulance, preferably with a cell phone so that they can answer questions about the incident. The casualty's dive computer should be transported with the casualty, and it is helpful if the person accompanying the casualty knows how to extract the dive history from the computer.
See Services directory for contact details.
See Services directory for contact details.
The retail dealers specialising in diving equipment are listed. Other sporting goods stores may also supply a limited range of diving equipment.
Scuba cylinder fills:
The listed dealers will fill cylinders for the general public. Some other service providers will fill for members only or for their own students or charter customers. See directory for more details.
Some dive operators will rent you equipment when you dive with them. Check when making a booking. The listed operators rent full Scuba equipment. Most charter boats will provide full cylinders on request.
See Services Directory for contact details.
Boat dives from a specialist dive boat. Usually one dive per trip, sometimes two. Booking essential. Some operators provide a divemaster, some will rent equipment, others only provide transport. Dives may be cancelled up to the last minute if conditions turn bad. If the trip is cancelled, you can expect a refund. Some operators will cancel if they think the dive will not be good, others will launch unless it looks too dangerous. Check terms before booking.
This listing is of operators who own and run a boat. Most dive shops and schools which do not run their own boat will book boat dives for clients on these boats. This is usually the way to go if you neet to rent equipment or need transport. Direct booking is appropriate if you have your own equipment. Most dive charters will rent cylinders.
Guided shore dives:
Shore dives led by a Divemaster. Usually one dive per trip. Booking usually required. Most operators rent equipment, some provide transport to the site from a specific assembly area, usually a dive shop. Check terms before booking
Places where divers gather to fill cylinders, have a drink and discuss diving. Clubs also generally offer training and equipment rental to members, and air and occasionally Nitrox and Trimix fills. Only dive clubs not exclusively affiliated to a dive school or dive shop are listed here. Some clubs welcome visitors to club dive outings, but non-members will usually have to provide their own equipment.
Cage Diving (sharks)
A small number of licenced operators offer open water cage diving to get up close to the great whites in their own environment. April to September is the peak time to see Great Whites in South Africa. There are morning and afternoon trips to Seal Island, where you can see the famous breaching Great White sharks of False Bay as well as cage diving, sometimes all in one trip. Not all cage diving is on scuba — in fact most is done on breathhold. Check when booking.
See Services directory for contact details.
Scuba equipment servicing and repair:
Scuba cylinder inspection and testing:
Dry suit servicing and repair:
Wet suit repairs and custom fitting:
Transportation to shore dive sites or boat launching sites is best done by road. In most cases there is no other option. The public transport in the region is not diver-friendly. Trains do not stop near most of the sites, Buses are infrequent, and also usually do not pass near the sites, and Mini-bus taxis are geared to maximising the number of passengers. If you are visiting for a short period and do not wish to rent a vehicle, it may be possible to arrange transport through a local divemaster or charter organisation. Ask if they have facilities for fetching you from your accommodation when you arrange a dive. Not all will offer this service, but it can be a great convenience if available. Some will even fetch you from the airport.
If travelling in your own or a rented vehicle, bear in mind that many dive sites, particularly on the Cape Peninsula, are notorious for theft from parked vehicles. Do not leave any items that may attract unwanted interest in the front of the vehicle, and ensure that the luggage compartment is secure. Dive clubs will sometimes arrange for an attendant to watch over parked vehicles during club dives.
The Street Guide to Cape Town, published by MapStudio and available at most book shops in Cape Town, is recommended for finding your way around to any of the sites north of Miller’s Point on the peninsula, and north of Steenbras river mouth on the east side of False Bay. This is adequate for most divers.
The map shows the most useful main road routes for getting around the dive sites. Road signs for these routes are as good as any in the region. The National roads are indicated with white numbers on blue signs and the prefix N. Regional routes are white on green signs prefixed with R. Main routes in the greater metropolitan area are prefixed with an M and are usually black on white signs.
Map links to Geocoded sites — Most of the dive sites harbours and slipways featured in this guide are Geocoded. Look in the left hand sidebar 'toolbox' for a "Map" link. If you click on this a choice of on-line zoomable street maps will become available. The Google maps have the advantage that a photo-overlay is available as an option.
Most of the dive charter boats of Cape Town are large rigid hulled inflatable boats powered by twin outboard engines. These boats are usually launched from a slipway for the day’s dives and are transported to the slipway on trailers. The boats are usually from 6 to 7.5m in length and are licenced to carry from 8 to 12 divers.
Bookings are made by phone, e-mail or in the shop. If you are not known to the operator you will be asked to present certification, and usually to sign a disclaimer.
Many of the dive charter boats in this area are purely transport facilities, leaving the responsibility for safety during the dive to the divers. If you want a guided tour, or need a buddy, check whether this is provided before booking.
Equipment is usually loaded onto the boats before launching or at a jetty near the slip. Diving suits are generally put on before boarding and worn during the ride, though occasionally jackets may be carried and put on at the site if the weather and sea conditions are suitable. Ask your skipper.
If you dive with unusual or specialised equipment such as large twin cylinders, side mounts, rebreather or bulky video equipment it is recommended that you clear this with the operator before booking. Similarly if you wish to dive solo or do scheduled decompression this should be cleared before booking, as some charter boats do not cater for these procedures.
There are no liveaboard dive boats based in Cape Town. However there are a number of large motor and sailing yachts that may be chartered, and there is no fundamental reason why they could not be chartered for a dive trip. Enquire about diving equipment and compressor rental when booking, as these will generally not be included.
Harbours and slipways
The Atlantic seaboard is served by the Hout Bay harbour and slipway, and the Oceana Power Boat Club slipway at Granger Bay, just west of the V&A Waterfront. The peninsula south of Noordhoek is also served by the Witsand slipway at the Crayfish factory near Scarborough.
Western False Bay launches are usually from the slipway at Miller's Point, though occasionally the slipway at the False Bay Yacht Club in Simon's Town is used, usually for the annual Scubapro Dive Festival. There is a slipway at Buffels Bay, but that is seldom used by divers.
There is a small and very shallow slipway at Rooi-els which can only be used by local residents who have permits, and is too small for the charter boats.
Lastly there is a slipway at Masbaai just east of Hangklip, which is open to the public, but is very shallow at low tide.
The regional and local hazards are of the following main types:
Many of the local dive sites require some level of fitness and agility to access as shore dives. Research the site, ask the locals, but the final responsibility is with the diver to assess each site personally. Beware of loose rocks and slippery slopes.
Sea and Weather conditions
These are variable, and even the experts get them wrong occasionally from forecasts and reports. You just have to estimate which area looks most promising, and go there to take a look. Be aware that a strong offshore wind can develop in a relatively short time, and plan accordingly. This is particularly prevalent in summer, when a strong south easter can spring up from a quiet morning, and make a long surface return swim hard work.
Many of the shore dive sites have limited access areas, which may vary in suitability with changes in tide or weather conditions.
The air and water temperatures can also be considered as hazards, particularly in summer on the Atlantic coast, where on an extreme day it is possible for the air temperature to be over 30°C and the water below 10°C. Both hyperthermia and hypothermia are possible on the same dive outing.
Boats and shipping
Some areas are more heavily used by seaborne traffic than others. In this respect, shore dives are not generally a problem, except for a few of the deeper shore dives on the west side of False Bay, in the vicinity of Miller’s Point. It is recommended to tow a brightly coloured SMB with an Alpha flag if you dive Boat Rock, Outer Castle, Oatlands outer reefs, or Photographer’s Reef as a shore dive.
Bakoven is a launching site for the National Sea Rescue Institute, and divers are required to tow a SMB when diving there.
The Law requires all powerboats to be in the charge of a licensed skipper who is theoretically aware of the international regulations regarding divers in the water and keeping clear, but in reality there are a number of skippers who are either ignorant or don’t care. Look out for yourself and do not fasten the SMB to your equipment in an area of boat traffic, in case it gets hooked up on a boat and you get dragged up. Report incidences of dangerous boat-handling to Table Mountain National Park offices if in their jurisdiction, or to the nearest harbour master.
Incidences of dangerous or illegal boat handling can be reported to the SA Police Services Water Wing in Simon's Town, but it appears that they only work alternating weekends, so there is a 50% chance there will be no-one there, and the regular police charge office does not know how to deal with this class of offense. More action is likely if you report the problem to SAMSA, (South African Marine Safety Authority). Try to provide as much information as possible to identify the offenders. Ideally the registration number of the vessel should be included, and a photograph can be helpful.
Marine life forms
Bluebottles or Portuguese Man o’ War are often seen in the bay, and can give an unpleasant sting, which may be dangerous to sensitive people. A wet suit is good protection. Avoid contact with your face; hands can be used to cover the exposed parts, or dive below the trailing tentacles, which can be quite long. Box jellyfish are also reputed to sting. Note that the stinging cells of bluebottles and jellyfish may become attached to your gloves or other equipment by contact during a dive, and may later sting you if they come into contact with unprotected skin. The trianglar shaped leafed succulent beach groundcover creeper the 'Sour Fig' provides excellent treatment. Rub some of the leaf`s juice on the sting. Ammonia also works well as does Meat Tenderiser.
Cape Fur Seals are not considered a hazard, though they make some people nervous. If they are relaxed, there are probably no Great Whites hunting nearby. If you ignore them they will typically get bored eventually and go away. They are big, strong, fast and have large teeth with strong jaws, so don't molest them.
Stingrays are theoretically a hazard. If you walk on one it may swipe you with its tail barb. This does not happen here, as we don’t walk on them. If you don’t try to grab hold they will not sting you.
Electric or Torpedo rays may shock you if you touch them. This is unlikely to happen as they are shy and usually avoid divers, but it could happen that you might touch one inadvertently when it is buried under the sand. This is highly unlikely, and will probably not do any lasting harm. Don’t worry about it, and don’t touch any disc-shaped ray that your buddy suggests you handle.
Sea urchin spines are a real but minor hazard. Surge or inattention may result in you getting spiked by these. If they bother you, get medical attention, but usually they will dissolve or if large may work their way out in time. A few spines is not usually considered a reason to abort a dive. There are so many sea urchins that it is only a matter of time before you get spiked by one. It is no big deal, the local urchins have fairly short and non-venomous spines, but they will go right through most suits and gloves.
There are various polychaete worms with bristles that may be an irritant. Avoid touching them. Gloves which are recommended as thermal protection will also protect against these bristles.
Red tides have occasionally produced irritant aerosols which can affect the respiratory passages. More often they do not and merely cause poor visibility, but bear this in mind. If by some chance you find yourself diving in waters where the air on the surface seems to be an irritant, breathe off your scuba gear until clear of the water. Associated toxins in the water may also produce a skin rash in these conditions, so get out as soon as possible.
Terrestrial life forms
Most of the terrestrial life forms in the Western Cape are not ordinarily considered a hazard to divers, though theft from parked vehicles at dive sites puts people at the top of the list.
Baboons in the southern peninsula and Rooi-els areas have become an occasional nuisance as they have learned to steal food from tourists, and as they are quick and strong and are armed with large teeth, they should be taken seriously. Some have learned how to open car doors and break into houses. Do not feed them, do not let them see that you are carrying food, and do not leave food where they can get to it. If you do you may be prosecuted, and will certainly be contributing to a problem that may result in serious injury to people and the necessity to kill the offending baboons.
There are a few species of venomous snake in the area, but mostly they are shy and keep away from people.
At some sites it is necessary to walk through bush with overgrown paths. Some of the bushes may have thorns. They will not usually penetrate a wet-suit, but be careful.
These are not generally considered a problem in the region. There are no endemic parasite-transmitted diseases. The area is free of Malaria, Bilharzia, Sleeping sickness and other tropical diseases. Aids can be avoided by the usual precautions, and municipal water supplies are safe to drink. Sewage is treated before discharge to the sea, and the greatest hazard is probably storm water runoff from the Cape Flats after heavy rains. Most of the dive sites are in areas well clear of major storm drainage, and if the water looks clear it should be fine.
Marine filter feeders should not be eaten after Red tides, but anything served in a restaurant should be safe.
Unfortunately some of our citizens and visitors are complete slobs and dispose of their garbage illegally, and broken bottles and similar hazards may be encountered. This can happen almost anywhere, but is most common at the roadside within throwing distance and along the paths where you need to walk. Some places are worse than others, and you will just have to be careful. Wet-suit boots are not always sufficient protection. Areas controlled by SAN Parks Board are usually better than those theoretically maintained by the City Council. Areas outside the municipal and Table Mountain National Park area appear not to be maintained at all.
The waters of the Cape Peninsula and False Bay support a thriving ecology of cool temperate marine organisms, many of them endemic to South Africa, or even smaller regions, and although the fish are not as spectacularly coloured as those seen in tropical waters, many are quite colourful in order to camouflage themselves among the extremely vivid invertebrates that cover the reefs.
There are a wide range of marine animals which one may see while diving this region, and they include some of the most awesome and spectacular encounters possible for a diver.
False Bay is one of the most reliable places to view Great White sharks, although rarely as a diver, and several other shark species are also frequently seen. The Sevengill or Cowshark can often be seen at a few sites, while Gully sharks and catsharks are more widespread. There are four common catshark species locally, from the colourful puffadder shyshark to the much larger pyjama shark. Other pelagic sharks are usually only seen on offshore "blue-water" dives off the south peninsula, and several large pelagic fish species can be seen on similar trips.
Large shoals of Yellowtail are occasionally seen at some dive sites, and on unpredictable occasions divers may be lucky enough to see Oceanic sunfish, Southern right whales, Humpback whales, Common, Bottlenose or Dusky dolphins.
The common Snoek, which is the cornerstone of a local linefishing industry, is very shy and hardly ever seen by divers, in spite of its habit of shoaling in large numbers.
Penguins and seals
There are colonies of African penguins in False Bay, but it is extremely unusual to see them during a dive. On the other hand, the Cape fur seals are both curious and unafraid of divers, and are very commonly seen, both in False Bay and on the Atlantic seaboard. There are several places where they can almost be guaranteed to be seen.
Reef fish of this region are most varied in False Bay, and most common in the restricted zones of the Marine Protected Areas, where they have been protected by law for several decades, though poaching still occurs, and enforcement is quite unreliable. Most of the reef fish are camouflaged to some extent. Many are silvery grey and countershaded, like the ubiquitous Hottentot seabream, the silvery Fransmadam and the Steentjie. Others have vertical bars or dark patches which may help break up their profile in kelp, such as White stumpnose, Zebra, and White steenbras, while many of the smaller species are cryptically coloured and blend very well into their environment. These are generally fish which spend most of their time on or very close to the reef, and their coloration is usually an indication of the typical colours of their habitat. These include various endemic klipfish, and a few blennies and gobies, the fingerfins, Cape triplefin, Smoothskin scorpionfish, two species of horsefish, a pipefish and the Rocksucker. There are also a few red fish, which are fairly visible, such as the very common Roman, and the less common Red stumpnose and Red steenbras. Most of the fish mentioned are solitary or found in small shoals, but there are also Strepies and Maasbanker which tend to shoal in fairly large numbers, and moderately large shoals of Hottentot are seen quite frequently. Galjoen are fairly rare and usually seen in small groups on top of the reef where there is a lot of wave movement, and the similar looking Cape knifejaw prefers deeper and high profile reef between the rocks. Seacatfish are shy and tend to spend the daytime in crevices and holes.
The sandy areas also have their characteristic fish, which include a few species of ray, soles, gurnards, a pufferfish and the Beaked sandfish, which is rare and shy by day, but may be seen in large numbers at night at some sites, when it comes out of the sand it hides in and swims around freely. A few species of klipfish are also sand-dwelling, with the various species preferring different densities of sand, with those preferring fine sand having a more snake-like body, whereas those in coarse sand being more robust. Their body pattern tends to match the type of sand as well.
Benthic invertebrates provide most of the bright colours on the reefs of this region, and the distribution of species is as characteristic of the different sub-regions as the depth and water temperature. The diversity is large, and there is a big variation in the predominant reef cover with both depth and geographical location. The characteristic reef life varies considerably between the east and west sides of the Cape Peninsula, and this is recognised as the border between the South Western Cape and Agulhas Inshore Bioregions. The vertical zonation is also characteristic of the different bioregions, so there can be very noticeable differences in what can be seen at the various sites.
There is a general tendency for a given area of reef to be dominated by a particular species of organism, for example, Common feather stars, Red-chested sea cucumbers, Mauve sea cucumbers, Red Bait or sea urchins, to the extent that a major part of the surface area is covered by the dominant organism. This does not mean that there is no variety, as there is a large range of habitats on most reefs depending on orientation and rugosity, and to a large extent, sessile organisms live where they can, and this is largely dependent on where the planktonic larvae find a foothold.
Pelagic invertebrates are by their mostly planktonic nature unpredictable as to when and where they can be seen. They include several species of jellyfish, a few species of comb jelly, a few sporadic siphonophores, salps and pteropods, and lots of things too small to easily notice. There are also squid, but they are very shy and are seldom seen by day.
Kelp forests are the most obvious seaweeds of Cape Town. There are three genera found locally, sometimes in close proximity. The most obvious is the Sea bamboo, which reaches the surface when fully grown, and has a thick stipe with a gas-filled cavity at the top, and which keeps the frond near the surface for maximum exposure to the light. This kelp is very common on the Atlantic seaboard, and is also found on both sides of False Bay, but more commonly towards the southern part of the bay.
The smaller Split-fan kelp grows on deeper reefs, and does not reach the surface. The stipes are shorter and there is no gas-filled cavity, so the fronds stay submerged in the darker waters. This kelp is found in deeper water than the Sea bamboo, with a similar geographic range.
The third is the Bladder kelp, which has clusters of long thin stipes, with long fronds and large numbers of small gas-filled bladders which keep the kelp upright and the fronds at the surface. This kelp is not found in False Bay, and is mostly seen near Robben Island.
Algal turfs and kelp forest understoreys.
Below the kelp fronds, the reef in shallower areas where there is enough light, may be covered by an understorey of assorted seaweeds, and the particular species will depend on a variety of factors, including the amount of light available, and the amount of water movement. As a rule, green and brown seaweeds will be found in shallower areas, and reds will be deeper, as they can survive with less light. The deepest are often the red coralline algae, which can form a dense turf on the upper surfaces of rocks.
Where the surf is too powerful or the light is too dim for other seaweeds, the encrusting coralline algae may still find a foothold and thrive. These red algae form a fairly hard and tightly adherent crust on the reef, and are also known as "pink paint", which is a fair description of their appearance — they don't look at all like seaweeds. Their range is almost anywhere in the region where enough light penetrates and there is no other occupant already on the reef.
Many of these wrecks have never been found, and many others have been broken up beyond recognition, or covered in sand, or in the case of Table Bay, been buried under land reclamation projects, but several are in diveable places and may be visited by divers if conditions are suitable.
Depths of the diveable wrecks vary from 3 or 4 metres, to more than 65 metres, and condition varies from half buried fragments of wood or steel, to ships that retain most of their original structure and appearance, and loom out of the depths as if sailing through the sand bottom.
Most are heavily encrusted with reef organisms, ranging from seaweeds in the shallow water to a large range of colourful invertebrates in deeper water. They also shelter a variety of reef fish, and may be visited by pelagic fish on unpredictable occasions. In effect, they serve as artificial reefs, and as a result are generally also of interest to divers who are not particularly interested in them as artifacts.
Many of the sites are characterised by interesting topographical features, including pinnacles, gullies, caverns, swimthroughs and overhangs. These features ore notable not only for their contribution to the seascape, but also provide major variations in available habitats at the site, and the result is a strong correlation between high biodiversity and interesting topography. The general topographical character of a site is dependent on the geology, and the granite sites are instantly distinguishable from the sedimentary sandstone and shale sites. The granite rocks are typically rounded and stacked as corestone boulders on outcrops of the same rock, often with white quartz sand between them, or as a gradually sloping base. These stacks of variously sized rocks often form pinnacles, and gullies in fairly random directions, and the overhangs and holes between them are in some cases large enough for divers to swim through, providing a spectacular reef structure.
The sandstone strata tend to produce formations dominated by the local dip and strike, and this is more predictable. However, the detail on a smaller scale tends to produce more small holes, crevices, ledges and ridges than the granite areas, and these are less spectacular as a general rule. There are exceptions, where the sandstone reefs are very craggy, usually where the dip is quite steep, but not vertical, and the shoreline is quite steep, but in a different plane to the dip.
Fortunately the old dictum "as above, so below" applies quite well, and the character of the reefs can be predicted fairly reliably by observing the adjacent shoreline landscape. The major exception to this rule is south of Smitswinkel Bay, where there are sandstones above the water and granite below.
Reference books on the ecology of Cape Town's waters:
From SURG, specifically for divers in this region: Available from selected dive shops and book shops in Cape Town, and direct from SURG.
Jones, Georgina. 2008. A Field Guide to the Marine Animals of the Cape Peninsula, SURG, Cape Town. ISBN 978-0-620-41639-9
Zsilavecz, Guido. 2005. Coastal Fishes of the Cape Peninsula and False Bay, SURG, Cape Town. ISBN 0-620-34230-7
Zsilavecz, Guido. 2007. Nudibranchs of the Cape Peninsula and False Bay, SURG, Cape Town. ISBN 0-620-38054-3
From other publishers, and of more general application:
Branch, G. and Branch, M. 1981, The Living Shores of Southern Africa, Struik, Cape Town. ISBN 0-86977-1159
Branch, G.M. Griffiths,C.L. Branch, M.L and Beckley, L.E. 2010, Two Oceans – A guide to the marine Life of Southern Africa, David Philip, Cape Town. ISBN 987-1-77007-772-0
Gosliner, T. 1987. Nudibranchs of Southern Arica, Sea Challengers & Jeff Hamann, Monterey. ISBN 0-930118-13-8
Heemstra, P. and Heemstra E. 2004, Coastal Fishes of Southern Africa, NISC/SAIAB, Grahamstown.
Ed. Smith, M.M. and Heemstra, P. 2003 Smith’s Sea Fishes. Struik, Cape Town
Stegenga, H. Bolton, J.J. and Anderson, R.J. 1997, Seaweeds of the South African West Coast. Bolus Herbarium, Cape Town. ISBN 0-7992-1793-X (rather technical)
Reference books on the Geology of the Cape Peninsula:
Compton, John S. 2004, The Rocks and Mountains of Cape Town. Double Storey, Cape Town. ISBN 1-919930-70-1