Castle Rock, its nearby neighbor Crystal Rock, is a not to be missed dive site with similarly sturdy currents that can be avoided by diving during slack tide.
The site itself is a very large pinnacle that descends to around 75 meters. The top can be reached at 4 meters making it possible for the dive to be relatively shallow. Most divers are taken to 20 meters where there is more marine life. Due to the current, divers normally descend and then safely hold on to the side of the reef. This enables divers to take in all the marine life and watch as everything swims by.
Most of the marine life is drawn to the site because the current provides ample nutrition. The marine life is accordingly vast in numbers. Amongst the list of ocean life that are commonly found here, you can normally see turtles, sharks, pygmy seahorses, leaf scorpion fish, the amazing blue ribbon eels, trevally, tuna, mackerel and bannerfish. It really is impossible to list all the fish that can be seen here as the site is extremely diverse, brimming with different types of fish.