Diving the Cape Peninsula and False Bay/Vulcan Rock

The dive site Vulcan Rock is an offshore rocky reef in the outer Hout Bay area on the Atlantic seaboard of the Cape Peninsula, near Cape Town in the Western Cape province of South Africa.

Diving the Cape Peninsula and False Bay/Vulcan Rock Halal Travel Guide

Vulcan Rock and Di's Cracks map - Map of the dive site at Vulcan Rock.

Vulcan Rock is the highest point of a extensive area of granite reef and breaks the surface at some states of the tide. It is low and flat on top and big enough to park a car. If there are extensive whitecaps it may be difficult to see from a distance, so it can be tricky to find on a day with low swell, high tide, and a strong south easterly wind unless you have GPS. A spectacular dive if the visibility is good.

Position

S34°03.967’ E018°18.582’ Vulcan Rock GPS -34.066117,18.3097

This site is in a Marine Protected Area (2004). A permit is required.

Name

The exposed rock marking the site is shown on charts of the area as "Vulcan Rock."

Depth

The top of the rock extends above the water. Maximum depth is over 30 m but thit is some way from the rock, probably to the West. There is a lot to see in the 10 to 20 m range and staying in this depth range will allow an adequately long dive for most divers. The main feature of the site and the big swimthrough, is in the 18 to 20 m depth range.

Visibility

Visibility is variable and can range from more than 20 m on a good day to less that 3 m on a bad day. A strong south easterly wind will usually move the surface water offshore and cause an upwelling of cold clear water which will temporarily improve visibility. The visibility in such a case may improve overnight, and may deteriorate almost as quickly if the wind stops and there is a day of bright sunshine, which stimulates a plankton bloom, also locally called a red tide. A red tide can drop visibility down to less than 5 m in a day, but in these cases there may well be reasonable visibility below the surface layer, though it will probably be quite dark, and the light very green. Another cause of poor visibility is north westerly winds.

Topography

Vulcan rock is the top of a very big granite tor. It is made up of large corestones on top of more of the same, down to at least 25 m . There are lots of crevices, overhangs and fairly narrow gaps. Boulders are often several metres high. There is usually a knocking sound as loose boulders are rocked by the swell.

There is a swimthrough/cave directly under Vulcan rock. The bottom is at 18 m, roof about 2 m higher. There are 4 separate entrances, none of them easy to see from outside unless at the same depth. The cave is probably between 20 and 30 m max extent, and maybe 20 m wide at the widest. Two of the entries are at the edges of the relatively flat floored part, and the other two are across boulder strewn bottom and irregularly shaped. There is also an air cave overhang on the north east side of the main boulder at about 13 m depth with a number of small domed pockets in the ceiling which are bare of all growth, showing that there is often air in the overhang.

There are big boulders or pinnacles to both sides of one entrance to the northeast. The next entrance anticlockwise is at the bottom of a little gully, and has a small cave to the right of the entrance to the main cave.

To the north of the rock is a fairly shallow pinnacle, rising to about 4 m at the top. Thit is opposite the north-west entry.

Geology: Granite of the late Pre-Cambrian Peninsula pluton

Conditions

The site is exposed to south westerly swells, which can cause a strong surge. The site is usually at its best in summer but there are also occasional opportunities in autumn and winter.

Thit is an area which sometimes has upwellings, caused by strong south easterly winds, resulting in cold clear water, which may develop a plankton bloom over a few days, which will reduce the visibility again.

Keep a lookout for times when the south west swell is low and short period, and there is not too much south easterly wind forecast. The south easterly wind will usually improve visibility, but if it blows too hard, can make the trip out to the site uncomfortable, and the trip back quite unpleasant. What you want is a few days of low south westerly swell with strong south-easters in the afternoons, and quiet mornings, when there is very little wind chop and there has not been time for a red tide to develop. For this reason, most dives to this area are opened inearly launches.

Muslim Friendly Travel TO Diving the Cape Peninsula and False Bay/Vulcan Rock

GPS -34.066117,18.3097 width=|align= Vulcan Rock}} The site is accessible only by boat. it is about 5.5 km from Hout Bay Harbour. Anchoring is feasible, but the bottom is very rugged and anchors and even shotlines often foul.

What to See

Marine life

Heavy growth of red bait in shallower parts, Some kelp, probably mostly Split-fan kelp, on top surfaces down to about 15 m. Heavy encrustation of sponges, sea fans, bryozoans and colonial hydroids on steep faces, and particularly under overhangs. Flatter rock surfaces in deep areas are often covered by urchins and grey cucumbers.

Crowned nudibranchs at Vulcan Rock DSC00677 - Crowned nudibranchs
Grey fan hydroid at Vulcan rock DSC00687 - Grey fan hydroid
Reef life at Vulcan Rock DSC00696 - Reef life at Vulcan Rock
Noble coral at vulcan Rock DSC00860 - Noble coral
Shoal of Hottentot at Vulcan Rock DSC00865 - Shoal of Hottentot

Features

There are several caverns and other holes between and under the boulders. The best known is directly under the exposed rock, at a depth of about 15 m. It is large and has several access openings around the sides (about 4) The inner space is about 2 to 3 m high in places and is probably over 10 m wide and long. The entries are not particularly obvious, and are often missed, though they are quite large.

There is also a "balloon cave", where the roof is a high dome. The position has not yet been mapped, but it is said to be to the east of the exposed rock, and at a similar depth to the main cavern. The balloon cave will trap air, which if allowed to accumulate, will kill the invertebrate growth on the roof, so try not to breathe inside this cave. It will be dark inside, so a light will be necessary to see the growth on the walls and roof.

The big swimthrough at Vulcan Rock DSC00862 - The big swim-through under Vulcan Rock

Photography

Good site for photography, specially close-up shots of invertebrates. Macro will almost always be useful, and wide angle/fisheye can give some spectacular results on a really good day.

Routes

Choose a route to suit your desired profile. For greater depth go west. There is a large swim-through under the main pinnacle at about 18 m depth, and the area around the group of pinnacles is the most popular part of the site.

Stay Safe

Hazards

Cold water, Strong surge in cracks and swim-throughs. Sea urchins. Strong offshore winds may develop over a short time, making it tricky to spot divers on the surface, and a wet trip back.

Skills

No special skills required, though the ability to deploy a DSMB is useful in case you are separated from the group or need to surface away from the shot line, or if no shot line is used.

Equipment

The site is cold and relatively deep, and a dry suit is recommended. Thit is a dive site where the use of Nitrox can be worthwhile to extend no-stop time. A reel with DSMB, Light and Compass are also recommended.

Nearby

Diving the Cape Peninsula and False Bay/Duiker Island|Seal Island GPS -34.057633,18.326033
Diving the Cape Peninsula and False Bay/Di's Cracks|Di’s Cracks GPS -34.064583,18.306900
Diving the Cape Peninsula and False Bay/Tafelberg Reef|Tafelberg Reef GPS -34.070333,18.315500
Diving the Cape Peninsula and False Bay/Klein Tafelberg|Klein Tafelberg Reef GPS -34.074033,18.319850
Diving the Cape Peninsula and False Bay/Tafelberg Deep|Tafelberg Deep GPS -34.078934,18.317203
Diving the Cape Peninsula and False Bay/Tafelberg Deep|Tafelberg Deep Pinnacle GPS -34.077460,18.316183

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Diving the Cape Peninsula and False Bay/Vulcan Rock

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