Diving the Cape Peninsula and False Bay/Sea Point Ridge Pinnacles
The site is conveniently close to the slipway at Oceana Power Boat Club in Granger Bay, and is shallow enough for advanced recreational divers It may be the closest granite offshore pinnacle to the slipway. The area is fairly well protected from south easterly winds.
This site is in a Marine Protected Area (2004). A permit is required
The name "Sea Point Ridge Pinnacles" is a simple geographic description. The nearest landmark on the shore is Sea Point (after which the suburb on the mountainside is also named), and a low ridge extends out along the seabed in a north westerly direction. There is one high spot marked on the chart at the pinnacles.
Maximum depth is about 27m, and the top of the outer pinnacle is about 17m. (Average depth is likely to be about (24m.)
Visibility will vary depending on the season and recent weather conditions. In summer after a strong south easterly wind and upwelling, it may be as good as 20m. Visibility may also vary significantly with depth. After an upwelling and algal bloom, surface visibility may be as low as 2 to 3 m, while below the thermocline it may open up to more than 15m, though it may be fairly dark.
The bottom in this area is low flat rock reef. The pinnacles are the only interruption of note in a large area, and they rise up from the bedrock at about 25m almost vertically to about 18m, and are fairly flat topped.
Geology: Pre-cambrian granite of the Peninsula pluton. The pinnacles may be quite near to the contact zone between the Peninsula pluton and the older Tygerberg formation, which is exposed at the shoreline just north of Sea Point.
The site is exposed to wind and waves fron the north west to the south west, so should be dived when the westerly swells are low, and is often good after strong south easterly winds, which reduce the swell and may bring clear cold water to the surface. The site is reasonably protected from south easterly winds, andvery well protected from south easterly swell, but if a cold front moves in then conditiona will deteriorate rapidly.
The site is usually at it's best in summer but there are also occasional opportunities at other times of the year.
This is an area which sometimes has upwellings, caused by the south-easterly winds, resulting in clear cold water, which will usually develop a plankton bloom over the next few days which will reduce surface visibility significantly. This site is deep enough that visibility at depth may differ significantly from at the surface.
This site is only accessible by boat, as it is nearly 2km offshore. It is about 6.6 km from the Oceana Power Boat Club slipway at Granger Bay.
The tops of the pinnacles have sparse Laminaria kelp forests, and the upper parts of the sides were heavily encrusted with small black mussel in November 2011. Lower down there are sea urchins, strawberry anemones and scattered sponges and colonial ascidians.
The main feature of the site is the pair of pinnacles on a relatively level base.
If the water is clear all the way down, wide angle natural light photos should turn out well, but you are more likely to be successful with macro equipment.
The site is small, and can be visited on a single dive. Start at the main pinnacle, which is where the shot should be, and swim around it. Make an excursion across the bottom to see if you can find anything interesting, and return to the shotline for ascent, or use a DSMB to mark your position.
There are no known site-specific hazards. The shipping lanes are to seaward of the site, and only small craft are likely to pass nearby.
No special skills required, the site is too deep for open water divers, and buoyancy control should be good enough to surface without a visible reference
The water is usually cold. A thick wet suit or a dry suit is recommended. Nitrox can significantly extend no-stop dive time if you are warm enough, and a DSMB is useful if you have to surface away from the shotline.