I was diving on Saturday in St. Maarten with Caribbean Dive College. We were diving on Cable Reef at about 45ft. The coral reef extends up to near the surface. Probably about 20 ft below the surface. The dive master first saw the shark at the top of the reef feeding on small fish. I didn't see it then. About 10 minutes later we saw the shark coming straight at us near the bottom of the reef. At first I was fine with it and then the shark came closer and closer and me breathing started to elevate a bit. It was an awesome site to see a shark coming head on like that with the blue water in the background. About 8ft from us the shark turned slightly and passed by us (that's when I got the picture) Then the shark did a 180 and headed back out.
I forgot to ask the DM about the shark species. I think from my limited research it is a Caribbean Reef Shark. It was between 4-5ft long from nose to tail. Maybe about 9-10" in diameter. It wasn't a very large shark. It has dark coloring along the edges of the fins.
Below are the pictures I took of it.