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. .
Vulcan rock is the highest point of a large 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 and a strong south easterly wind unless you have GPS. A spectacular dive if the visibility is good.
The site is acessible only by boat. it is about 5.5km from Hout Bay Harbour. Anchoring is possible, but the bottom is very rugged and anchors often foul.
This site is in a Marine Protected Area (2009). A permit is required.
The rock marking the site is shown on charts of the area as "Vulcan Rock."
Maximum depth is over 30m but this is some way to the north of the rock.
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 25m . 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 18m, roof about 2m higher. There are 4 seperate 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 20m 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 13m 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 bolders or pinnacles to both sides of one entrance. 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.
Geology: Granite of the late Pre-Cambrian Peninsula pluton
The site is exposed to south westerly swells, which can cause a strong surge. The site is usually at it's best in summer but there are also occasional opportunities in autumn and winter.
This 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.
Heavy growth of red bait in shallower parts, Some kelp, probably mostly Split-fan kelp, 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.
Good site for photography, specially close-up shots of invertebrates.
Choose a route to suit your desired profile. For greater depth go north past the north pinnacles which do not break the surface. There is a large swim-through under the main pinnacle at about 18m depth.
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.
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.
The site is cold and relatively deep, and a dry suit is recommended. This 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.