Cape Town Diving

by Morné Christou and Alistair Downing
(This is an excerpt from the article published in Alert Divert Autumn 2012 edition)
Winter diving at its absolute best
­­­Cape Town’s dive sites come under the general category of temperate reefs. We do not have a particularly large variety or numbers of fish, and many of them are cryptics, so can be difficult to spot. However, when you find them they are often extremely beautiful in their detail and colouration. Our major attraction is benthic invertebrates, the little critters which live on and around the rocks, and these are both plentiful and ecologically diverse. Many of them are also very colourful and make great photographic subjects.
There is a wide range of sites: some suitable for night dives, some accessible from the shore, and others only suitable for boat access. Depths range from shallow sub-tidal to over 50 m. The geological structure varies and this gives sites a variety of topographical characters, and the ecological character also varies considerably with general location and depth. Cape Point is considered the boundary between two marine bio-regions. You can do a hundred dives in Cape Town and still not really know the area.
The Weather
Cape Town diving moves around with the weather.
The South Western Cape has a Mediterranean-type climate, with most of its rainfall during the winter months from June to September. There is a large seasonal effect, as the prevailing winds tend to be generally westerly in winter and south-easterly in summer, with more unpredictable autumn and spring conditions. There are very few periods when there is bad diving weather for more than a few days in a row, and similarly there is seldom a run of more than four or five days of really good conditions. Predicting diving conditions is best left to locals who dive a lot and know how to read the forecasts, and is only reasonably reliable over the short term (say two to five days), though sometimes we can get it right as long in advance as a week.
Swell forecasts are usually quite reliable in the short term, and are of great importance to dive planning. The waters are temperate, with a maximum temperature in False Bay of about 23°C in summer, and minimum of around 8°C on the Atlantic side. In winter it is more commonly between 14°C and 17°C, and most of the diving is then done around Simon’s Town. Visibility can also vary considerably, with occasional days with more than 20 m, and other times less than 2 m, depending on the previous few days’ weather.
There are over 150 named dive sites from Robben Island to Cape Hangklip, within the range of day trips from anywhere in Cape Town, and more are found every year. Most of these sites are very weather-dependent, and it is impossible to forecast with any confidence whether any given site will be diveable on a specific day, but there is usually somewhere that is worth a dive if you really want to get in the water.
WINTER in the South Western Cape is characterised by disturbances in the circumpolar westerly winds, resulting in a series of eastward moving depressions which bring cool cloudy weather and rain from the north-west, and the strong south-westerly winds over the South Atlantic produce the prevailing south-westerly swell typical of the winter months, which beat on the exposed Atlantic coastline and east side of False Bay. The mountains of the Cape Peninsula provide protection within False Bay from this wind and from the south-westerly waves. In spite of this gloomy-sounding forecast, winter usually provides us with some of our best diving conditions, as the sheltered east side of the Peninsula may have mild water temperatures, flat seas and good visibility while it is raining and windy above the water. The south-westerly swells are slowed by the continental shelf and refracted and diffused round the Cape Peninsula, so they have lost much of their energy by the time they curve in towards the shore on the east side of the peninsula. The irregular form of the coast here also protects some areas more than others, so the choice of dive site is dependent on the recent weather patterns.
Between the cold and rainy fronts there are frequently days of little or no wind, and mild to warm sunshine, when the water is flat and clear and the diving is wonderful. Water temperature during winter is usually between 13°C and 17°C, so a 5 mm suit (at least) is recommended, with the full set of boots, gloves and hood. Most of the shore dives are relatively shallow, in the order of 8 m to 15 m maximum depth, which makes a drysuit less advantageous, but getting out of a wetsuit in the wind and rain pushes the drysuit up again as a desirable option, particularly if you plan to dive more than once per day. For boat dives a drysuit is great because not only are you warmer during the dive, but the boat trip is far more pleasant. It is nice to have the choice.
’THERE IS A WIDE RANGE OF SITES: SOME SUITABLE FOR NIGHT DIVES, SOME ACCESSIBLE FROM THE SHORE, AND OTHERS ONLY SUITABLE FOR BOAT ACCESS.  OUR MAJOR ATTRACTION IS BENTHIC INVERTEBRATES, THE LITTLE CRITTERS WHICH LIVE ON AND AROUND THE ROCKS, AND THESE ARE BOTH PLENTIFUL AND ECOLOGICALLY DIVERSE.’  
WINTER WRECKS
Wreck diving enthusiasts have a choice ranging from old wooden wrecks in Simon’s Bay to the Smitswinkel Bay wrecks, which are five ships sunk as artificial reefs on a sand bottom at roughly 30 m. The wrecks of Smitswinkel Bay are among the best-known and most popular boat dives of the Cape Town area. The water is deep enough to reduce surge significantly and shallow enough for recreational divers, and the area is fairly well protected from the prevailing swell. The depth also protects the wrecks from the worst of the storm surge which would otherwise have broken them up much sooner. The wrecks are easy to find, large and sufficiently intact to be recognisable, and have developed a thriving ecology which includes a few relatively rare organisms. To the north, the HMSAS Transvaal F602 was one of three Loch class frigates transferred to South African naval forces while under construction. The ship was laid down at the yard of Harland and Wolff as HMS Loch Ard , and was launched at Belfast on 2 August 1944 as HMSAS Transvaal . The ship was sold for scrap and scuttled by explosive charges in Smitswinkel Bay to form an artificial reef on 3 August 1978. The wreck is 94 m long, and lies more or less upright on a flat sand bottom with bows to the north-east. The wreck retains its shape to some extent, though rust is taking its toll and the mast has fallen to the port side. The bows have broken from the rest of the hull just aft of the foredeck winch and have fallen over to starboard. Aft of this the foredeck has sheared off the topsides along the starboard gunwale and subsided into the wreckage. The upper deck aft of the forward gun mount has collapsed, taking with it the remains of the forward superstructure. Aft of this the upper deck is open above a machinery compartment, where some heavy equipment is still moderately intact. The quarterdeck is in relatively good condition. The deck plating has wasted away between the frames in many places, but the hull plating is mostly intact and the rudder and shaft brackets are in good condition. The wreck of the trawler Orotava lies a few metres off to starboard, about 20 m forward of the transom.

The MFV Orotava was built in 1958 by Cook, Welton and Gemmel Ltd, of Beverly, East Yorkshire. It is the larger of the two trawlers and lies on the sand at about 34 m with the top of the funnel at about 23 m, and is heeled to port at an angle of about 20°. The vessel has an asymmetrical superstructure with the enclosed part offset to port and a covered walkway on the starboard side. There are several holes in the sides and upper deck where plating has rusted away leaving only the frames and an open hatch on the foredeck forward of the winch, giving access below. The third wreck, the Princess Elizabeth , is about 75 m to the south. The MFV Princess Elizabeth was built in 1961, also by Cook, Welton and Gemmel. It was badly damaged by a fire and was donated to the False Bay Conservation Society along with the Orotava by Irvin and Johnson. In August 1983 the vessels were towed out to Smitswinkel Bay and scuttled. It lies on the sand at
36 m with a slight list to starboard. The depth at the top of the wreck is about 28 m. The gap from the Princess Elizabeth to the Good Hope is about 10 m directly astern, to the east. HMSAS Good Hope was another of the Loch class frigates. The ship was laid down in November 1943 as HMS Loch Boisdale, and was launched at Blyth on 5 July 1944 as HMSAS Good Hope and went into service on 9 November 1944. The vessel saw service as a convoy escort during the closing stages of World War II and was for many years the flagship of the S.A. Navy. The ship was sold for scrap and scuttled by explosive charges to form an artificial reef at 15:45 on 18 June 1978. It sank in five minutes. The wreck lies upright on a flat sand bottom with bows to the south. Most of the hull plating has rusted away on the quarter deck leaving mainly frames. The mast has fallen and is lying over the starboard side. The main deck has partly collapsed and has caved into the wreck, still attached along the sheer line. The interior of the hull is now accessible from many places where the plating has wasted away, and also through a number of openings on the deck. A large rectangular opening roughly amidships opens into what was probably a boiler room, which is still quite crowded with equipment. At the southern end of the group, the Rockeater is a relatively bulky wreck for its length compared with the frigates, and at 65 m is quite a bit larger than the fishing boats Orotava and Princess Elizabeth . The MV Rockeater was built in New Orleans in 1945 as a coastal freighter for the United States navy. The ship was bought by Ocean Science and Engineering (South Africa) in 1964 to be used for marine prospecting. After years of work the Rockeater was in poor condition and no longer seaworthy. It was planned to use the ship as a naval target, but because of fears that she might sink at her moorings in Simon’s Town, it was decided to
THERE ARE OVER 150 NAMED DIVE SITES FROM ROBBEN ISLAND TO CAPE HANGKLIP,  AND MORE ARE FOUND EVERY YEAR.    
donate her to the False Bay Conservation Society. The Rockeater was towed to Smitswinkel Bay on 15 December 1972 and scuttled. The wreck lies upright on flat sand at about 34 m, with bows to the west. The drilling derrick lies on the sand to the north-west of the superstructure, and the helicopter pad has collapsed to port. The rest of the vessel is largely intact but has lost a lot of superstructure plating. The hull lies on the bottom buried to what looks like near the working waterline.
There are a large number of openings into the wreck. On the waist deck there is a big rectangular hole in the deck plating and a number of smaller hatchways with raised coamings. There are several doors into the superstructure, and large areas of superstructure sides where the plating has wasted away almost completely, leaving only frames. There is a lot of obscure structure on the deck, which was probably part of the drilling equipment, most of which has been removed or has collapsed. The wrecks are too deep and dark for much seaweed, but are heavily encrusted
with invertebrates, some of which are seldom seen anywhere else but on the Smits wrecks. Reef fish are regularly seen, and some pelagic fish have been seen passing by, including oceanic sunfish and yellowtail.