Diving the Cape Peninsula and False Bay/Sentinel
The dive site Sentinel is a shoreline rocky reef in the Hout Bay area on the Atlantic seaboard of the Cape Peninsula, near Cape Town in the Western Cape province of South Africa.
This is the place on the Atlantic seaboard where the 30m contour is closest to the shore
This site can be dived from a boat or from the shore.
The site is about 2.5km from Hout Bay harbour slipway.
Shore dive: There is a parking area at S34°03.553’ E018°20.690’ just beyond Hout Bay Sewage Works building.
South and east of the Sentinel (mountain peak)
This site is in a Marine Protected Area (2009). A permit is required.
The name "Sentinel" is the name of the steep rocky peak on the mountainside above the site.
The maximum depth of 30m requires a 500m swim out and is over sand. Most of the site is shallower than 10m.
Gradually sloping fine sand bottom at 30m, with occasional rock outcrops as it gets shallower, sloping up to shoreline reef and boulders at about 15m. Coarser sand in shallower parts. Reef is mostly moderately low profile, but with the occasional big rock. Surf zone is rounded boulders of about 1m size range. There are a number of sub-sites in this area. The Sentinel is considered by some to be in front of the vertical cliffs, and is an area of flat reef with lots of kelp and often box jellyfish, and some big boulders. The Pinnacles are a group of rocks just past the end of Hout Bay harbour, near the sewage works. (the outfall pipe opens much further to the south)
Geology: Late Pre-Cambrian granite corestones of the Peninsula pluton. with occasional shoreline boulders of the overlying Table Mountain sandstones.
Best after south easterly winds (summer). Exposed to south westerly swells and to wind chop from south easterly winds.
Adequate parking at the end of the gravel road. See Hazards.
Box jellyfish are common near the bottom over sand. The deep rock outcrops are covered with common feather stars. There is fairly thick kelp forest inshore. Hottentot, occasional anemones, small swimming shrimps over the rocks, West Coast rock lobster, small red and brown algae, small sponges, sea fans, starfish, hydroids, and black mussels have been seen.
30m shore dive: Entry about 50m beyond parking place, surface swim to where the depth should be sufficient. This will be easiest if you have a submersible echo sounder, or a GPS on the surface marker, otherwise use compass bearings from the chart. Dive and swim out until depth is 30m. To return swim a compass course of north magnetic, ascending gradually until about 6m. and swimming in mid water to the surge zone near the shore. Entry and exit may be a bit rough in the surf and boulders. If the return is done along the bottom and the dive is on air, decompression will be required.
This area is reported to be a high risk for assault and theft from vehicles. There is also some risk from boats as there is considerable traffic in the area of fishing boats, tourist charter boats and dive charter boats. Cold water. Strong onshore winds may develop over a short period, making exit shore tricky. Access to entry/exit points is over a boulder beach.
No special skills required. The site is suitable for snorkeling. Some fitness and agility is needed for shore access, and there is a long swim to do a 30m dive.
A large surface marker or an escort boat with Flag Alpha is recommended if you plan to go far from the shore, as this area is frequented by tour charter boats and fishing boats. If you plan to do a shore dive to 30m, a compass is essential and Nitrox will allow a no-decompression dive.