Diving the Cape Peninsula and False Bay/Castle Rocks
This article is a travel topic
The dive sites at Castle Rocks and Parson's Nose are a group of inshore rocky reef areas in the Castle Rocks restricted area on the False Bay coast of the Cape Peninsula, near Cape Town in the Western Cape province of South Africa.
These sites are good for fish and invertebrates, and in many places have spectacular topography. All are accessible as shore dives, but the shore access is not easy.
The name "Castle Rocks" applies to the point as a whole and the offshore rocks to the South East. The point is a small rocky peninsula that is nearly an island at high tide. The name also applies to the Marine Restricted Zone which stretches from Rumbly Bay, just south of Miller's point, to Baboon Rock, just south of Partridge Point. "Parson's Nose" refers to a small rocky point in the Castle Rocks South area.
The depth of the different sectors varies, but the maximum is probably about 18m, with an average bottom depth nearer 10m
North: This area has a fairly shallow rocky bottom with granite boulders and outcrops of moderate height near the entry point. Further east is a series of big outcrops and boulders, some reaching almost to the surface, with gullies and gaps between. Around the point there are a ridges and gullies running more or less north-south.
Along the north side about 20m off the big boulder with two vertical cracks, there are two entrances to a swim-through at about 9m depth, which can be found by following the edge of the kelp zone. The swim-throughs join under the boulders and split into three exits, to the left, sloping upwards, in the centre sloping upwards and to the right into a hole surrounded by boulders. There is a belt of sand bottom to the north of the north entry, separating the Castle Rocks reefs from the Shark Alley and Pyramid reefs. This belt is about 350m long and is parallel to the north coast of the Castle Rocks peninsula. The width varies from almost nothing in places to about 30m, and it tends to be wider inshore, with a narrow section about halfway along. The bottom in this belt is fine sand inshore, and sand and pebbles further out.
Pinnacles: To the northwest of the point is an area of large boulders and pinnacles. The pinnacles rise from a bottom of about 15 to 18m, and in one case to within 3m of the surface, and are huge sheer sided boulders. There are two major groups, the first one is a single large block with a crack along the middle. The second, in line with the first, but further out, is a jumble of rocks with caves, gullies and overhangs. There are more pinnacles further out, but they are not as high.
Point reefs (Outside Castle): Beyond the point are large high profile parallel ridges and gullies running approximately north-south (010° magnetic). The bottom of the deeper gullies is sand with steep sided ridges between, of varied length, width and height. Further out the gullies are wider and the ridges shorter, but the general tendency is the same. The ridges are the same granite as the point. Further out the reef thins out and there is more coarse shelly sand and the wave ripples may indicate a northerly wave direction.
Further to the south of this is a mixture of high and low ridges with sand bottomed gullies and gaps between them. Some are high, from the bottom at 14m up to 7m, others lower, down to less than a metre. These can be quite spectacular in good visibility.
South (Inner Castle): This is the sandy bay visible from the roadside to the south of the point. There is fine sand bottom sloping from about 2m deep near the entry to about 12m at the outside of the large rock group to seaward of the sand patch. This group is big granite ridges with some small to medium sized holes and tunnels, most of which are too small to enter. There are deep gullies at the back of the offshore rocks, and further south is flat fine sand bottom with very small ripples and occasional widely spaced low rock outcrops.
Geology: Granite of the Pre-Cambrian Peninsula pluton
Usually considered to be a winter dive but there are also occasional opportunities in spring and autumn. The site is well sheltered from north west wind and chop. Swell from the south west or south east will cause surge, and a strong south east wind will produce an uncomfortable surface chop which can make some of the exit areas difficult and may reduce visibility in a few hours. Judge by the conditions at the entry point and the colour of the water further out.
None. Security at the parking area is said to be poor. Lock up your valuables where they can not be seen. The grassy patch at Castle Rocks is a pleasant spot for a picnic, but it may attract the attention of baboons.
 Get in
There is limited parking on the gravel shoulder on both sides of the main road (M4). The path to the shoreline starts at steps at the apex of the bend in the road and goes between the houses. If you are parked further north, the gravel access road also leads to the path.
The top of the path leading to the entry areas starts at the extreme left foreground of the photo. The path can be a bit slippery and is not all in good repair, but it is not a difficult climb for a fit person. There are entry and exit points north and south of the grassy patch.
North entry: It is often convenient to use the sheltered area inshore of the rounded rock ridge at S34°14'19.98" E018°28'35.92", in the middle of the picture, and to swim out round the left end of the rock. The ridge is roughly parallel to the shoreline, which provides a fairly sheltered little gully. In the centre background is Boat Rock, or Bakoven Rock, and the top of Pyramid rock can just be seen closer inshore to the left, beyond the kelp. This entry point can be used for dives to Shark Alley and Pyramid Rock, and anywhere on the North side of Castle Rocks. The boat just visible on the extreme right is probably anchored at Outer Castle. The north access depends to a large degree on tide and swell. Make your own decision after checking on site.
There is also an entry point right at the tip of the point on the north side at S34°14'20.62" E018°28'39.38'. To get there go towards the tall rocks and skirt them to the left until you reach a series of Red-bait fringed rocks. These drop off directly into quite deep water, but are not an easy exit, specially at low tide.
The south side has more options for entry. The rocky little beach nearest the road is generally usable. The photo shows the entry and exit point most popular on this side, which is right beside the large rock in the middle left of the photo. Stay to the seaward side close in to the high ridge at S34°14'22.43" E018°28'35.95" for exits. The gully to seaward of this ridge is deceptive and can be an unpleasant exit if a wave catches you as the surge can be strong.
You can use the large flat topped Black rock further to seaward at S34°14'22.84 E018°28'38.25" for entry and exit if it suits your dive plan. The top of this rock is almost black, and can be slippery when wet, however it is reasonably flat, and there is a convenient crack and ledge to help get back on if the tide is not too low.
All these shore access areas require walking over irregular rocks and boulders, some of which may be loose.
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 Marine life
There is a belt of heavy Red-bait growth fairly close to the surface, and below this there is a zone where sea urchins dominate, particularly on near horizontal surfaces. There are fairly dense kelp forests in the north entry area, between the point and the southern rocks and on the submerged rocks between the southern rocks and the mainland. In the deeper reef areas there is often a dense cover of feather stars and sometimes red sea cucumbers. This is a site well known for variety and size of fish and a diversity of invertebrates. Sometimes even a whale.
The swim-through pinnacle at S34°14.363' E018°28.820' in the Northern Pinnacles part of the site is a group of large outcrops capped with a large flattish boulder. There are two distinct and spacious swimthroughs under this pinnacle from the sand tongue more or less north east onto the reef.
The site is good for fish and invertebrate photography. Almost any camera setup will be usable if conditions are good, but macro and wide angle arrangements with external strobes will usually be most versatile.
 Stay safe
No special hazards other than those associated with shore access at the sites.
The Southern part of Castle Rocks includes the group of large rocks in the middle right of the photo. The water inshore of these rocks is fairly sheltered and has a sandy bottom with scattered rock outcrops where the kelp is visible. This is a popular training area for entry level divers, and is also suitable as a base point for night dives.
A moderate level of fitness and agility is required for shore access at these sites.
No special equipment is required. A light is useful for looking into dark holes and overhangs and for restoring colour loss due to depth. A compass can help you to keep track of your position and is useful for finding your way back underwater and at night.