Along the black sandy floor you will encounter more bizarre and fascinating marine creatures than you could wish for. (Dive-The-World.com)
Smugglers Cave: Water washed sandy floored caverns, accessible at low tide, flooded at high tide (make sure you are aware of tide movements). (coastalstays.com)
Really nice hard coral formations there and the Yap Cavern is actually a big cut into the wall with a whole bunch of huge coral heads and then you can swim through a maze and through tunnels with white sandy floor and you see a very large school of bumphead parrot fish in there in the morning and some really beautiful anemones and soft corals. (divehappy.com)