Name: The area is shown on SA Navy charts as "Castor Rock". Depth: Maximum depth is about 18 m to the south, and 22 m to the north. The highest point on the reef is about 7 m deep. There are a few other pinnacles above 12 m. Marine life: A large variety of invertebrates, and if you do your safety stop near one of the pinnacles you may be visited by shoals of reef fish including Hottentot, Galjoen, Dassie and Fransmadam. Relatively large numbers of Bank Steenbras have been seen here, but mostly quite small. Zonation is variable according to depth and surface orientation. Some kelp above about 10 m, but small and sparse. Red bait and other large ascidians fairly numerous, but not densely packed. There are patches of encrusting sponges and ascidians on relatively horizontal areas. Moderate numbers of elegant feather stars are scattered around. Common feather stars are also common in some areas, mostly where it is fairly steeply sloped. There are also clumps of red chested cucumbers, mauve cucumbers, striped anemones, bushy corallines, encrusting corallines and Coral Plocamium. There are lots of gorgonian sea fans along the reef edges in the 15 m to 20 m depth range. Palmate, Sinuous, and Flagellar fans appear to be equally common. There are huge numbers of golden sea cucumbers on the reef slopes to the north and more expectedly, also in the sand along the reef margins. Occasionally virtual carpets of hairy brittle stars can be seen at the north end of the reef. Photography: Good photographic site. Most equipment will be usable depending on visibility. Topography: This is an extensive reef of granite. Basically a very large area of moderate to low outcrops with occasional high areas, small gullies, ridges, boulders, small crevices and overhangs. The edge of the reef is penetrated at irregular intervals by small sandy bottomed gullies between the ridges. The reef is divided into two large lobes by a pair of narrow sand tongues which encroach into the reef from the east and west, and nearly meet just north of Wonders Pinnacle on the west side of the south lobe.