Diving the west coast of South Africa

This article is intended to provide the already qualified scuba diver with information which will help to plan dives in the waters of the west coast of South Africa, whether as a local resident or a visitor. Information is provided without prejudice, and is not guaranteed accurate or complete. Use it at your own risk.

Understand
In comparison with the tropical waters more familiar to many divers, the water is cold – it can be anywhere from about 20ºC down to 8ºC. It can be dark, and visibility can vary considerably – 8 m is considered fairly good, though it occasionally exceeds 20 m, and less than 3 m is considered bad. Locals generally consider 5 m to be the lower limit of acceptability for recreational diving, but visitors with limited time available may have little option if they want to get a dive or two in during their stay, and some of the service providers will accommodate diving on days when the locals will do something else. Significant bottom currents are rare but surface currents can be sufficient to cause problems for divers who delay descent, and one can drift a long way during decompression. Surge is common and can be tricky in a large and long period swell, which is not uncommon. There are sharks, including great whites, but they are seldom seen. Surface wind chop does not usually affect underwater conditions, but can make the boat ride or surface swim uncomfortable. The usual dive boat is a large RIB with two outboard engines, launched from slipways, though access to the boat for the divers might be from a jetty. Shore entry diving is an option over much of the region depending on diver fitness and access to the water from the road. Much of the coastline is quite rugged and exposed where there are good dive sites inshore, but there are a few notable exceptions with easy and well protected access.

The whole region is in the Atlantic Ocean – the official boundary with the Indian Ocean is at Cape Agulhas – but the ecological boundary between west and south coast is at Cape Point, and both local divers and marine biologists recognise a significant difference between the "Atlantic side" and False Bay.

General topography
Most of the west coast is relatively straight and exposed to the wind and waves from the north-west through to southwest, with the major exceptions of parts of False Bay and Saldanha Bay. St Helena Bay and Table Bay are protected from south-westerly swells but exposed to north westerly winds and wind waves. The general trend of the coastline in a south-easterly direction allows strong Ekman transport during south-easterly winds. This drives the upwellings in summer.

Dive sites are either wrecks or rocky reefs (or both), and depth can vary dramatically. The continental shelf is relatively narrow south of Cape Columbine to Cape Point, so the depth tends to increase rapidly with distance from the shore, while north of Cape Columbine the seabed shelves more gradually and inshore water tends to be shallower. Granite reefs can drop vertically in walls as much as 25 m high, but are usually less dramatic in profile, Most popular granite dive sites have at least some vertical faces in the order of 3 to 5 m high, often with overhangs and a few small swinthroughs formed by boulders bridging gullies. The granite has usually weathered as corestone tors, stacks of boulders which have become rounded along fracture edges over millions of years, but remained largely more or less in their original positions relative to each other.

Marine ecology
South Africa's coastal waters can be divided into a number of biogeographical regions, though there is generally not a sharp distinction between them where the boundaries have been placed. There is more of a gradual change along the coast, from the tropical waters of northern KwaZulu-Natal to the cooler waters of the south coast.

The one place where there is a relatively distinct change over a short distance, is at Cape Point, where the waters of the east and west sides of the Cape Peninsula support noticeably different ecologies, and even here there is a significant overlap of resident organisms.

There are a large proportion of endemic species along the west coast, though not as much as on the south coast.

The marine ecoregions
The regions of interest to recreational divers are the coastal ecoregions, which are accessible and shallow enough to dive. These are considered to extend from the shoreline to the break of the continental shelf, so most of the area is far too deep to dive.
 * The cool temperate Benguela ecoregion extends from Sylvia Hill in Namibia to Cape Point. The cold Benguela Current is the major influence, and the region is characterized by large-scale intensive upwelling and nutrient rich water. At the south eastern end of this region, the break at Cape Point is very distinct in the inshore depth ranges, but in deeper areas it has been chosen as the depth contour at of 150 m, to approximately south of Cape Agulhas. This line is more consistent with the mixing zone of the Benguela and Agulhas currents,
 * The warm temperate Agulhas ecoregion extends from Cape Point to the Mbashe River. The Mbashe River was chosen as the most appropriate boundary between the subtropical Natal province to the north, and the warm temperate Agulhas region to the south, but change is gradual between these regions. Upwelling on the south coast of South Africa is largely driven by the Agulhas current and the continental shelf. This form of upwelling forces cold deep water up onto the continental shelf, but not necessarily above the thermocline. In the region east of the Agulhas bank, wind enhanced upwelling, occurring mainly in summer, augments the current driven upwelling, bringing the colder deeper waters to the surface. This enhances biological productivity by supply of nutrients to the euphotic zone (where plants have sufficient light to flourish) which fuels phytoplankton production, and rocky shores that are supplied with the nutrient rich water support rich algal biomass. The annual chokka (squid) spawning takes place largely in this region.

The ecoregions that meet at Cape Point on the Cape Peninsula are very different in terms of the life they support, and this remains so, even though there is some migration of species between the two sides.

The west coast of the peninsula and northwards is subject to upwelling when the southeast wind blows in summer. This upwelling is the strongest wind-driven upwelling in the world, with rates of 30 m per day having been recorded. Sea surface temperatures can drop in hours as cold water from the deep ocean wells up replacing inshore water blown offshore under the influence of the wind and the rotation of the earth. This is the time to dive the Atlantic side. The water is cold, with temperatures as low as 7ºC, but the visibility can be in the tens of metres.

The upwelled water carries minerals and other nutrients resulting from the constant snow of dead animals, decayed matter and groundwater runoff sinking to the deep ocean, where there is no light, so plants cannot use it. When it reaches the shallows, phytoplankton in the surface water use these nutrients to grow and reproduce rapidly. so that about a day after the southeaster has dropped, the surface water is so thick with phytoplankton and zooplankton feeding on it that the visibility can drop down to two or three metres. This is not much fun to dive in, but it drives a very productive ecosystem. The layer of plankton may only be a few metres deep, as it blocks the light from reaching deeper, so the phytoplankton bloom is restricted to the surface layer. Visibility can be much better below the bloom, but it will be quite dark and the thickness of the murky layer is somewhat unpredictable. Although relatively uncommon, the southeaster can also cause upwelling in winter, and if the swell is low, the diving can be good.

In winter, the west coast is battered by northwest storms and the whole region gets powerful south-westerly swells coming in from the storms of the southern ocean, so west-facing coast often becomes too turbulent for diving. These energetic waves result in Cape Town being a favoured location for big wave surfing, and ensure that west coast reef fauna is robust.

Though there has been eastward spread of kelp forests in the 2010s, kelp forests are a characteristic feature of the west coast. Kelp is a protist, not a plant, since it doesn't have vascular systems or roots. However it photosynthesises like a plant and it looks a bit like a plant and is referred to as seaweed. Kelp is a phenomenal converter of sunlight and carbon dioxide into organic matter. The most obvious species on the west coast known as kelp is the "sea bamboo", Ecklonia maxima, which grows to about 12 m height and has flat fronds that float at the surface, buoyed up by a gas filled stipe (the kelp stem) with a wider bulb float at its top end. The kelp attaches the base of the stipe to rocks using a tangled mass of root-like structures known as a holdfast. When kelp plants are torn loose by storm waves, they can be driven onto the beach by wind and wave, where they make a significant contribution of available organic matter to the sandy beach ecology.

Floating kelp can also be a problem for boat propellers and for divers. It spreads out at the surface and hinders surface swimming. This can be solved by swimming a metre or two below the surface, but that requires proper planning to ensure that enough gas is available for the dive as well as the surface swims. When unavoidable, moving slowly and calmly and pushing it apart as you swim reduces wasted energy. Finning through kelp on your back just gets the fronds caught up around the top of the cylinder, which is a massive drag. A snorkel allows face down surface swimming through this type of kelp. Kelp can be very useful to hold onto in surge, and a large kelp forest absorbs a lot of wave energy.

The other common kelp of the west coast is the split-fan kelp Laminaria pallida which thrives in the shallower waters to the north of the region, but further south seldom reaches the intertidal zones, and tends to form fully submerged forests on the upper surfaces of rocks below the Ecklonia canopy. The third west coast kelp is the giant kelp Macrocystis pyrifera, which is found here in a relatively stunted form, seldom more than about 12 m long, and hardly ever seen by divers. Range in South Africa is from Cape Point to Paternoster in sheltered inshore areas.

Kelp forests have many impacts on the ecology of the coast, both as a shelter and substrate for many organisms, and as a food source. The fronds provide shade for animals living in the understorey and this shade also inhibits growth of seaweeds that need a lot of light and enhances growth of shade-tolerant seaweeds. The reduced water movement allows more delicate animals to live in the kelp than would otherwise survive.

Equipment
The equipment recommended is basic scuba equipment with good thermal insulation. A 7 mm wetsuit is good enough for some divers, but others prefer a dry suit with a good undersuit, particularly for longer, deeper or multiple dives. Hood and gloves are strongly recommended, though occasionally divers have been known to do without.
 * A dive light is an option for most dives, but there are many places where having an artificial light source will greatly enhance the dive.
 * A deployable surface marker buoy (DSMB) is strongly recommended for boat dives, particularly when there is a choppy surface, a strong wind, or the dive plan does not include surfacing at the shotline.
 * Sufficient weight to allow a controlled safety stop with near empty cylinders, but not so much that buoyancy control at depth is compromised, and definitely not so much that the buoyancy compensator cannot provide neutral buoyancy at all planned depths and positive buoyancy at the surface. As a first approximation the BC should be able to support all the lead, and the lead should be able to sink the suit.
 * A permit is required to dive in MPAs, but the same permit is good for any MPA.
 * Other equipment may be necessary or desirable to suit a specific dive plan.

Dive sites
The Western Cape province is the most south western province in South Africa. It includes a large proportion of South Africa's tourist destinations and attractions, amongst which are several of the better known diving destinations.

Lambert's Bay
Lambert's Bay is a small fishing town of the west coast of the Western Cape 280 km (170 mi) north of Cape Town. This is a stretch of coastline exposed to wind and seas with a westerly component. It is not generally considered a scuba diving destination, but is quite popular for freediving for kreef (west coast rock lobster) in season.

Dive sites include:

Elands Bay
Eland's Bay is a small fishing town in the Western Cape about 220 km (2½ hours drive) north from Cape Town. It is not generally considered a scuba destination, but is fairly popular for freediving for rock lobster in season. It is a more a surfing destination and is also known for caves with rock paintings. It is not in an MPA, so no permit is required for scuba diving. Lobster diving requires a permit specifically for that activity.



Paternoster
Paternoster is a small fishing town on the west coast of the Western Cape. It is not generally considered a scuba diving destination, but is quite popular for freediving for lobster in season, and has a few wreck sites worth diving after the day's catch has been landed if conditions are good. This is not a MPA, so a permit is not required for scuba diving, however rock lobster collection requires a permit.

Dive sites include:

Saldanha Bay
Saldanha Bay is a major port for ore export, and fishing harbour adjacent to several Marine Protected Areas and terrestrial nature reserves. It is not well known as a scuba diving destination, but there is a commercial diving school in the town and some recreational diving is also done nearby.

Dive sites include:

Dassen Island
Dassen Island is a small island nature reserve off the west coast of the Western Cape. It is not generally considered a diving destination as it is not easy to get there, but there are a few dive sites including some wrecks if you are in the area.

Dive sites include:
 * House Bay
 * Protea Rock
 * Southern Author wreck

Silwerstroomstrand
Silwerstroomstrand is a beach to the far north of Cape Town. It is not generally considered a scuba destination, but there are a few sites.

Dive sites include:

Cape Town


The waters of include the Atlantic seaboard, on the west of the Cape Peninsula which is cool to cold temperate, and False Bay, which is also cool temperate, but significantly influenced by the warmer waters brought down the east coast by the Agulhas current, and has some ecological similarity to the south coast.

Cape Point is accepted as the boundary between the cool temperate Benguela ecoregion of the west coast, and the warm temperate Agulhas ecoregion of the south coast. Unlike the other boundaries between the marine ecoregions, which are diffuse, the ecosystems vary quite distinctively over a short distance at Cape Point, due to the change from the dominating influence of the warmer Agulhas current to the east to the cold Benguela current to the west.

There are many endemic species of fish, invertebrates and seaweeds, as well as a variety of other more widely distributed organisms, and a large number of shipwrecks, some of which are highly regarded as dive sites. False Bay is sometimes host to wandering fish from warmer regions, and occasionally even turtles, brought in on the currents from the east coast.

The mountainous Cape Peninsula, which separates the Atlantic Ocean from False Bay, also protects the coastal waters on each side from wind and waves from the other side, making it possible to have year round diving, but seasonal variations in where to dive and what to see, as there is a significant and noticeable difference between the ecosystems on the alternative shorelines.

For a listing and detailed descriptions of most of the over 250 named dive sites in this region, some including detailed maps, refer to Diving the Cape Peninsula and False Bay

Betty's Bay
is a small resort town in the Overberg district of the Western Cape. It was a popular freediving area for recreational abalone collecting before the fishery was closed to the public and became a major poaching problem.
 * Betty's Bay

Hawston
Hawston is a small resort and fishing town in the Overberg district of the Western Cape

Hermanus
is a small harbour town in the Overberg district of the Western Cape, well known for whale watching. There is a commercial diving school and a recreational dive shop/school, both in the new harbour.

Gansbaai
Gansbaai is a small harbour town in the Overberg district of the Western Cape, well known for cage diving with great white sharks.

Dive sites include:
 * - A famous historical wreck.
 * Birkenhead Rock
 * Dyer Island - Cage diving with great white sharks

Get help
Emergency services
 * Recompression facilities &mdash;
 * Divers Alert Network (DAN) has a branch in South Africa Their toll free line from within the country, and regular line will get you the 24-hour emergency hotline. If you are a DAN member and are involved in a diving accident, contact them first and they will make the necessary arrangements through whichever other organisations are most appropriate.
 * National Sea Rescue Institute contact details
 * Sea Rescue emergency number from cell phones - 112
 * Air Sea Rescue Unit -
 * Western Cape
 * Bakoven -
 * Gordon’s Bay -
 * Hermanus -
 * Hout Bay -
 * Kommetjie -
 * Knysna -
 * Lamberts Bay -
 * Melkbosstrand -
 * Mossel Bay -
 * Mykonos -
 * Simon’s Town -
 * Strandfontein -
 * Table Bay -
 * Witsand -
 * Yzerfontein -
 * Ambulance - 10177
 * Police - 10111. Emergency calls to ambulance or police numbers will be routed to the relevant Sea Rescue authority if you do not have the local Port Control number.

Get service
There are dive shops and schools at several of the destinations in this region, but for more complicated service most of the facilities are in Cape Town.

Stay safe
Marine life forms

The Great White Shark is found in False Bay and Gansbaai, and is considered by some to be a danger to divers. This may be true, and it would be prudent to avoid them when possible. There are areas and seasons when they are more common. If you want to see the sharks, do a cage dive with a licensed operator. If you do encounter one during a dive, try to avoid looking like a seal. Some divers suggest keeping close to the bottom, most recommend getting out quickly. Hanging around in mid-water or on the surface is not recommended by anyone. If there are Great Whites around, a safety stop may not be safe. On the other hand, if you do a cage dive, some cage operators will tell you that the noise of open circuit scuba keeps the sharks away, but this may be to save them money by not providing air and space on the boat for scuba equipment. Cow sharks are not kept away by scuba noise.

An analysis of sightings by shark spotter personnel has shown that some conditions are correlated to shark sightings:


 * More sharks are seen in summer than in winter. This trend has been known for a long time, and is confirmed by the data.


 * Sea surface temperatures of 16-20 °C increase the probability of a sighting &mdash; the probability of a shark sighting at Muizenberg is significantly higher when the water is warmer. This is thought to relate to the preferred temperature range of many of the shark’s prey species.


 * There is a greater probability of shark sightings from three-quarter (waning) to new moon than at full moon.

Bluebottles or Portuguese Man o’ War are often seen in the bay, and can give an unpleasant sting, which may be dangerous to sensitive people. A wet suit is good protection. Avoid contact with your face; hands can be used to cover the exposed parts, or dive below the trailing tentacles, which can be quite long. Box jellyfish are also reputed to sting. The stinging cells of bluebottles and jellyfish may become attached to your gloves or other equipment by contact during a dive, and may later sting you if they come into contact with unprotected skin. The triangular shaped leafed succulent beach groundcover creeper the 'Sour Fig' provides excellent treatment. Rub some of the leaf`s juice on the sting. Ammonia also works well as does Meat Tenderiser.

Cape Fur Seals are not considered a hazard, though they make some people nervous. If they are relaxed, there are probably no Great Whites hunting nearby. If you ignore them they will typically get bored eventually and go away. They are big, strong, fast and have large teeth with strong jaws, so don't molest them.

Stingrays are theoretically a hazard. If you walk on one it may swipe you with its tail barb. This does not happen here, as we don’t walk on them. If you don’t try to grab hold or harass them they will not sting you.

Electric or Torpedo rays may shock you if you touch them. This is unlikely to happen as they are shy and usually avoid divers, but it could happen that you might touch one inadvertently when it is buried under the sand. This is highly unlikely, and will probably not do any lasting harm. Don’t worry about it, and don’t touch any yellowish brown disc-shaped ray that your buddy suggests you handle.

Sea urchin spines are a real but minor hazard. Surge or inattention may result in you getting spiked by these. If they bother you, get medical attention, but usually they will dissolve or if large may work their way out in time. A few spines is not usually considered a reason to abort a dive. There are so many sea urchins that it is only a matter of time before you get spiked by one. It is no big deal, the local urchins have fairly short and non-venomous spines, but they will go right through most suits and gloves, and will leave pinhole leaks in your previously dry suit.

There are various polychaete worms with bristles that may be an irritant. Avoid touching them. Gloves which are recommended as thermal protection will also protect against these bristles.

Red tides have occasionally produced irritant aerosols which can affect the respiratory passages. More often they do not and merely cause poor visibility, but bear this in mind. If by some chance you find yourself diving in waters where the air on the surface seems to be an irritant, breathe off your scuba gear until clear of the water. Associated toxins in the water may also produce a skin rash in these conditions, so get out as soon as possible.

Terrestrial life forms

Most of the terrestrial life forms in the Western Cape are not ordinarily considered a hazard to divers, though theft from parked vehicles at dive sites puts people at the top of the list.

Baboons in the southern peninsula and Rooi-els areas have become an occasional nuisance as they have learned to steal food from tourists, and as they are quick and strong and are armed with large teeth, they should be taken seriously. Some have learned how to open car doors and break into houses. Do not feed them, do not let them see that you are carrying food, and do not leave food where they can get to it. If you do you may be prosecuted, and will certainly be contributing to a problem that may result in serious injury to people and the necessity to kill the offending baboons.

There are a few species of venomous snake in the area, but mostly they are shy and keep away from people.

At some sites it is necessary to walk through bush with overgrown paths. Some of the bushes may have thorns. They will not usually penetrate a wet-suit, but be careful.

Microbiological hazards

These are not generally considered a problem in the region. There are no endemic parasite-transmitted diseases. The area is free of Malaria, Bilharzia, Sleeping sickness and other tropical diseases. AIDS can be avoided by the usual precautions, and municipal water supplies are safe to drink. Sewage is normally treated before discharge to the sea, and the greatest hazard is probably storm water runoff after heavy rains. Most of the dive sites are in areas well clear of major storm drainage, and if the water looks clear it should be fine.

Marine filter feeders should not be eaten after Red tides, but anything served in a restaurant should be safe.

Artificial hazards

Some residents and visitors dispose of their garbage illegally, and broken bottles and similar hazards may be encountered. This can happen almost anywhere, but is most common at the roadside within throwing distance and along the paths where you need to walk. Some places are worse than others, and you will just have to be careful. Wet-suit boots are not always sufficient protection.

Read
Branch, G. and Branch, M. 1981, The Living Shores of Southern Africa, Struik, Cape Town. ISBN 0-86977-1159

Branch, G.M. Griffiths,C.L. Mranch, M.L and Beckley, L.E. Revised edition 2010, Two Oceans – A guide to the marine Life of Southern Africa, David Philip, Cape Town. ISBN 978 1 77007 772 0

Gosliner, T. 1987. Nudibranchs of Southern Arica, Sea Challengers & Jeff Hamann, Monterey. ISBN 0930118138

Heemstra, P. and Heemstra E. 2004, Coastal Fishes of Southern Africa, NISC/SAIAB, Grahamstown.

Ed. Smith, M.M. and Heemstra, P. 2003 Smith’s Sea Fishes. Struik, Cape Town. (Authoritative, large and expensive)

Regional references
Stegenga, H. Bolton, J.J. and Anderson, R.J. 1997, Seaweeds of the South African West Coast. Bolus Herbarium, Cape Town. ISBN 079921793X (rather technical)

Cape Town and the Cape Peninsula and environs
See Cape Peninsula and False Bay publications