Castle Rock is basically a square lump of rock, about the size of a football field, sitting alone in an area with a limestone and sand bottom. The top of the rock is at 12 m (40 ft) and usually the shot line is dropped right on top to allow divers to adjust their gear before "plunging" over the edges of the rock formation.
The site has lots of macro fauna all over it with lots of nudibranchs grazing. One wall is covered in tiny yellow zoeanthids.
There are of undercuts at the 20 m (62 ft) max depth where you may sight a cray, or two, usually missing their horns from past encounters with divers. Southern Blue
Devils also hide in the cracks and holes.
