Diving the Cape Peninsula and False Bay/GB Reef

The dive site GB Reef is an offshore rocky reef east of the Whittle Rock area on the central part of False Bay, near Cape Town in the Western Cape province of South Africa.

Map needed

Found during a multibeam sonar survey of False Bay by Wreckless Marine in about 2022, and first dived in August 2025 by Wreckless Divers. GB Reef is the largest of the Off-Whittle Far Eastern Reefs. Nice reef, pleasant, but not very spectacular topography.

-34.22701518.609881 GB Reef: S34°13.6209' E18°36.5973', East of Whittle Rock, west of the SATS General Botha wreck, about halfway across False Bay between Simon's Town and Gordon's Bay. A granite outcrop, rising from about 42 m on the sand to about 32 m at the top of the southwestern ridge. The reef is the closest rocky outcrop to the wreck of the General Botha. This site is not in a Marine Protected Area, and a permit is not required.

The name "GB Reef" is in recognition of it being the nearest rocky reef to the wreck of the SATS General Botha, also known to local divers as the "GB".

Maximum depth is about 42 m on the sand, and the top of the ridge is about 32 m. (Average depth of a dive is likely to be about 37 m.)

Visibility is likely to be much like at the reefs of the Whittle Rock area of similar depth. It is deep enough to usually be below the algal bloom and associated heavy plankton layer which often develops after a sunny period. The first dive was in about 20 m visibility, which is unlikely to be frequent.

A fairly large but quite low profile granite outcrop, with occasional higher ridges. Much of the reef is criss-crossed by closely spaces joint planes, and there are several low-lying sandy patches within the perimeter of the reef.

Geology: Precambrian granite of the Peninsula pluton, surrounded by sand. Possibly the easternmost exposed part of the Peninsula pluton in the bay.

The site is exposed to wind and waves from all directions, so should be dived in low swells and light winds, and is likely to be at its best in winter but there will also be opportunities during the rest of the year. This is an area which has a thermocline in late summer, and the visibility may be better at depth when there is an algal bloom in the surface water, caused by strong sunshine in summer, resulting in a top layer of poor visibility with clearer but dark water below.

The site is only accessible by boat. It is about ?? km from the slipway at Miller's Point, but boats may also leave from Simon's Town jetty or Gordon's Bay. On a good day in a fast boat it is a bit more than a half hour run from Simon's Town Jetty, a distance of about ?? km. Occasionally boats may leave from Gordon's Bay Old Harbour or Harbour Island marina, which are both about ?? km away.

No known routes.

• 
  Basket star on sponge at GB Reef
• 
  Deepwater sea urchin at GB Reef

The occasional ridges, which tend to support more varied invertebrate cover.

Macro with artificial lighting. and wide angle with natural lighting if you are lucky with visibility and natural illumination.

There are no known site-specific hazards other than the depth. Most of the site is within the depth range usually accepted as suitable for recreational diving, but not for emergency swimming ascent. Surface currents due to wind are likely and may take the divers away from the descent area during an ascent with decompression stops.

The competence to follow suitable decompression procedures is strongly recommended. This includes carrying and using appropriate gases and deploying a decompression buoy to mark the position of the divers during ascent.

Adequate and reliable alternative breathing gas supply, as the depth is beyond the range for which emergency swimming ascent is a reasonable response. A decompression buoy is strongly recommended, and may be required by the service provider. A fully redundant emergency gas supply is recommended. Use of breathing gas mixtures appropriate to the depth is recommended.

34°15′7″S 18°34′17″E

Whittle Rock and other offshore dive sites of False Bay

Other offshore dive sites of False Bay:

• -34.22798318.6381671 SATS General Botha
• -34.2337318.587722 Bill Liltved's Reef:
• -34.239418.5807833 Off-Whittle Ridge
• -34.24743318.56194 Whittle Rock
• -34.24818.5813335 Bruce's Mark
• -34.2525518.5784836 Sandy-top Ridge
• -34.25295518.608277 South Island Reef
• -34.25511618.5518838 Josh's Reef
• -34.25901718.5661679 Wreckless Ridge
• -34.2682818.58061710 Southwood's Corner
• -34.27158318.54538311 Lonehill Reef
• -34.27356718.56681712 Deep South Whittle Reef

Back to the Alphabetical list of sites, or list of reef dive sites in the Whittle Rock and surrounds offshore area

Other regional dive sites:

• Dive sites of Table Bay and approaches,
• Dive sites of the Cape Peninsula west coast
• Dive sites of the Cape Peninsula east coast
• Dive sites of False Bay east coast
• Fresh water dive sites of the Cape Town Metropolitan Area