Difference between revisions of "Diving the Cape Peninsula and False Bay/Percy's Hole"
Revision as of 11:49, 30 May 2011
This article is a travel topic
This one of the best known and most interesting sites on the east side of False Bay. It is topographically varied and has a high biodiversity. The site is usually dived from the shore and the entry points are well protected though require some effort to reach from the road.
18km South of Gordon’s Bay, on the headland just to the north of the beach at Rooi-els.
This is not in a Marine Protected Area. A permit is not required.
No-one seems to know who Percy is or was, and why this site should be named "Percy’s Hole", but it has been known by this name since before 1983.
The bottom is generally from 14m to 20m, unless you swim way out where 23m can be found on the sand. The subtidal shoreline is unusually steep, and depths of over 10m are very close to the water's edge. This site is probably the place in False Bay where the 20m contour is closest to the shore. A depth of 14m can be found within about 30m of one of the entry points, and within 10m horizontal distance of the nearest shore.
Visibility is not usually very good. 3 to 5m is fairly common, but occasionally 10m+ has been reported. Good visibility is sometimes associated with cold water and often with long periods of offshore wind (South easterly) and low westerly component to the swell, but is not predictable with any certainty.
General layout The entry point is in the small gully to the left of the main gully, running inshore of, and parallel to, the two ridges. There is a stepped wall on the outside of the outer ridge, which is a good site for a night dive.
The gully drops down to 14m depth between the heads. There is a stepped wall (2 levels) with an overhang at the bottom to the south, and extensive rocky reefs to the north, with a swim-through inshore of the exposed rock pinnacles (Seal Rocks). To seaward of seal rock there are high reefs, and to the north of these the bottom slopes down to a sand bottom at 23m.
North east side of entry gully, sharp right: The mouth of the gully drops to 14m. There are some big boulders lying on the bottom and a tall narrow outcrop with kelp on top. The shoreline wall to the north has quite a deep overhang and runs approximately east magnetic until it forms a strait between Seal Rock reef and the shore. It gets shallower until a huge boulder almost blocks the gully, close to where the bigger Seal Rock breaks the surface. Under this is the tunnel (swim-through) in a deep part of the gully. It has a nearly level bottom covered with small water-rounded boulders, and vertical access at the south end and in the middle. The north end access is stepped down into the tunnel by about a metre.
Beyond the tunnel the strait widens and is partly blocked by some large outcrops and boulders. The Seal Rock reef continues parallel to the shoreline for some way then tapers down. Beyond this, to seaward, the bottom flattens out and becomes a gently sloping pebble/gravel bed, ending at sand, This reef comprises large sandstone outcrops, and has deep overhangs along part of its length at the bottomof the north-eastern face. One overhang extends about two metres under the rock with a maximum height of about a metre, and is several metres long.
Far north-east: The shoreline of the north east of the north cove includes a small cave at the end of one of the deep gullies that indent the shoreline in this area. The gully bottom is at about 9m, with small to medium rounded boulders on the bottom, then steps up vertically to about 5m depth at the mouth of the cave.
The cave is about 7m wide at the mouth, and the roof is arched and extends to slightly above sea level at most tides. The cave is straight and approximately semi-elliptical in plan, extending roughly 20m into the rock in line with the gully. The floor slopes gently up and the roof down to the back. There are a few large boulders and a lot of small ones on the floor, but the entrance is at all times at least partly visible from the back and would be classed as a cavern for diving. There is a fairly deep horizontal crevice at the base of the north side which is sometimes occupied by large numbers of White seacatfish.
Straight out from gully, and a bit to the right: From the gully mouth straight out there are low rocky outcrops. About 30m out on bearing 030° magnetic there is the start of a high broken ridge of rock tending 355° true for 60m with gaps, overhangs etc. The outcrops are of moderate and variable height.
This reef appears to be a continuation of the ridge to the north east of the gulley above sea level. The top of this ridge gets slowly deeper further out before ending quite suddenly. The far part of the reef is fairly low, followed by a high pinnacle and dropoff to seaward, and borders on course pebble gravel with occasional small boulders. (This is also the end of the reef described in the previous section).
To the south west of this is a low area with sand and pebble bottom and occasional low rock outcrops that starts quite close inshore, about 45m to seaward of the ridge in front of the entry gully, and extends to magnetic north as far as the edge of the reef. Much of this sandy area is in line with the entry gully, and may well be an underwater extension of the same topographical feature, formed during the last ice age when the whole of False Bay was above sea level.
The far end of the ridge then tends about 087° magnetic for about 60m and rises from a pebble bottom at about 18m to the top at about 12m. The wall is very sheer in places, with long deep overhangs at the bottom. The shoreward end is shallower and the ridge tapers down to meet the bottom which shelves up more gradually. The seal rock reef is inshore of this area.
South west side of gully, sharp left: The depth is about 12m at the base of the shore wall which is to the left of the gully (south west). The wall is in two sections, The deeper section is from the bottom at about 12m to about 6m, where it shelves shoreward to the ridge which breaks the surface to the south west of the gully mouth. The deeper section of the wall is undercut quite deeply but with not much headroom, and the bottom is sandy near the wall.
Geology: Ordovician Sandstones of the Table Mountain group, probably Peninsula formation (uniformly light grey, medium to coarse grained, well bedded quartzitic sandstone. Strike is roughly north east, and dip about 25° south east.
The site is exposed to south west swell. Long period swell will result in poor visibility and a fairly rough entry and exit. The site is usually at its best during or after south easterly wind in summer, but there are also occasional opportunities in winter when there has been a spell of calm weather with no big storms in the South Atlantic.
This is an area which sometimes has cold water upwellings after the south east wind, and occasionally these upwellings bring clear cold water and excellent diving.
Keep a lookout for times when the swell forecast is short period and low, or is not from the south west. Do not worry about south easterly winds, as this site is very well protected from them, and is divable when the wind is almost too strong to stand at the parking area. If you dive in these conditions, avoid sufacing more than 50m or so offshore, as the wind may then make a surface swim back to the guully uncomfortable and strenuous.
Winter storms may bring in broken kelp to cover the bottom below the walls, and the visibility is then likely to be poor due to suspended organic matter.
A combination of a high tide with moderate south west swell can make conditions tricky for exits at the gully when waves can break over the ridge from the south west and cause a rip current to flow out through the gullies and heads which can be difficult to swim in against. In these conditions consider alternative exit points or move in along the bottom, pulling yourself along the rocks and kelp.
Paved parking bay on seaward side of the road (R44). Sometimes crowded in the Kreef (Rock lobster) season but usually adequate.
Shore or boat: Dives can be done from a boat from Rooi-Els, Gordon’s Bay or Hangklip, but unless you can arrange to launch at Rooi-Els it is a long ride.
Access to the slipway at Rooi-els is limited to local ratepayers, and the slip is very small and the water shallow, so it is not often used for diving.
For this reason dives at Percy's are mostly done from shore entry, as the shore access is quite good, though quite a long walk and the path is rough, steep in places and may be slippery when wet.
How to get there by road: Parking is on the seaward side of the road from Gordon's Bay (R44 - Faure Marine Drive) on a paved parking bay at S34°17.404’ E018°49.398'.
Paths on site: Walk down the path that goes to the right from the north end of the parking area (see map) then turns left at the grassy patch (see middle foregound of photo), then turns right again towards the gully. This part of the path may be a bit obscured by bush, but it runs parallel to the rocky ridges which slope down to the gully. The middle part of this section of the path is often muddy due to springs, and it becomes rocky lower down.
The path down to the gully is in the middle of this view, taken just below the right hand cross, which has no known connection with the site name. The path is almost always muddy and after rains there may be a small stream running under the bush. The path is slippery and frogs may be seen.
Entry and exit point Entry and exit is in a shallow branch of the gully to the south of the main inlet. This entry point is quite well protected from waves and is accessible when the swell is reasonably low. If inaccessible, visibility will be poor, and it will not be worth diving. The gully may be safe for entry and exit even if there is a significant amount of white water at the mouth, as the side gullies and kelp dissipate a lot of the power of the waves. (See note under "Conditions"). Swim out to the gap between the rocks at the gully mouth and descend to 14m in the centre.
Alternative entry and exit points: There is also a north entry area with a fairly steep but less muddy climb, which starts at the road sign for a sharp curve slightly north of the parking area. This path leads down to a sloping rock at the south of the little cove at the bend in the road, just north of the seal rock reef.
The dip of the strata is quite steep here, and it can be a little tricky when getting out to avoid slipping on the wet rock. Barnacles help with grip but are unfriendly to dive suits and bare skin. The path is also steep enough to need the use of hands at one point, but there are adequate handholds so this is not a big problem. Conditions will vary depending on tide and swell.
The marine life is varied and abundant, There is a variety of soft corals, colonial ascidians and sponges here that are not easily found on this side of False Bay.
This is a popular area for ring netting of West coast rock lobster in season, and at most times of the year they are fairly common. There are hardly any abalone left, but the closely related "Venus ear" or "Siffie" can be found amongst the red bait pods in the shallows.
An unusually large variety of nudibranchs may be found here if you have a sharp eye, lots of luck and time to search. Some of them, such as the Giraffe-spot nudibranch, are tiny and hard to see, while others such as the Orange dorid, which live on an encrusting sponge of the same colour, are incredibly well camouflaged. In compenstion, there are bigger brightly coloured species such as the Gas flame and Ink-spot nudibranchs which are both larger and usually contrast strongly with the background, making them easy to see. The silver tipped nudibranch is also easy to find, simply because there are so many of them.
This site provides a habitat range which is uncommon in sites accessible from the shore, and there are large areas of shallow water species, dominated by the large solitary ascidian known as "Red-bait", which in turn provides a highly rugose habitat sheltering and providing a substrate for a large range of smaller invertebrates.
In deeper water the red-bait is less common, and the reefs themselves are complex and have highly structured surfaces, with large and small crevices and profiles ranging from relatively flat to very rugged, also encouraging a wide variety of benthic invertebrates. As a result, this site has a variety of gorgonian sea fans, soft corals, noble corals, false corals and other bryozoans and cnidarians. There are also a fine variety of sponges and colonial ascidians.
Fish and other vertebrates
Fish are not specially plentiful, but a fair variety have been seen, including a few which are seldom seen so far south.
The doublesash butterfly fish is a south coast endemic species. False Bay is the extreme western part of their range, but there is a reasonable chance of spotting them at this site, particularly if the water is not too cold. Unfortunately that means they are usually seen when visibility is poor, but they are not particularly shy, and do not usually go very far when startled, so you have a good chance of observing them for a while. Often seen in pairs, or small groups, but more commonly alone.
The Koester is also an endemic south coast species and seldom seen in this area. It is one of the rock cods, and those seen here have been juveniles,
Strepies are one of the more common species, and are almost always seen in fairly large shoals. Their behaviour is typical of schooling fish, in that their movements are remarkably well co-ordinated.
Other fish seen here include shoals of Maasbanker, Hottentot seabream, Jutjaw and a few Roman and Galjoen. The area is not protected from fishing, and the recreational fishermen have taken their toll.
Shark species are mostly small puffadder shy sharks and pyjama catsharks, but bigger sharks have occasionally been seen.
South African fur seals are frequently seen here, but usually in small numbers, and Southern Right whales occasionally pass by further offshore.
This is a very good site for photography of invertebrates, and a number of sightings of rare organisms have been made here. Visibility is seldom very good, so Macro equipment or an external flash is recommended. Wide angle can also work if you are lucky enough to have good visibility.
These routes are shown on the map.
Shore access requires a walk down a muddy and slippery path and some scrambling over rocks. Surge may be strong in the gullies and swim-through. At high tide there may be a rip current flowing out through the heads. This can be overcome quite easily by pulling yourself along the bottom. If you dive during a strong south easterly wind, avoid swimming back on the surface, as the wind will hinder your progress, and could blow you offshore.
There may be broken glass or other garbage on the path; use footwear.
There are baboons at Rooi-els. There have been no reports of them troubling divers ar Percy's Hole, but take the usual precautions and don't leave food in sight, or car doors unlocked or windows open.
No special skills are required. The site is suitable for novice divers and some areas are good snorkelling for those who can go deep enough.
Moderate fitness and agility is required for shore dives.
This is a good site for night dives as they can be done close inshore along the wall, though the climb back up the path may be tricky in the dark.
A light is useful for illuminating under overhangs and restoring true colour. A compass is convenient for keeping track of where you are. Hard soled booties or some other form of shoe are strongly recommended for the walk to and from the gully. Your footwear will get muddy.