When we went to St. Thomas last February we dove with Admiralty Dive Center. Their website is: www.admiraltydive.com
We were very impressed with them. They picked us up with their boat right at the cruise terminal. Our divemaster even carried our bags. She wouldn't let us carry them.
Our captains name was Marty and we loved him, I can't remember the divemasters name, but she was great too.
We did two dives. The first was a wreck in 90 feet of water called Miss Opportunity. It was a great wreck dive, but it is considered advanced and I wouldn't do it if you haven't done a wreck dive before. The visibility wasn't that great on that dive. I don't know if it was just that day or what, but we only had about 20 feet max visibility.
The second dive was Flat Cay (I think). It was one of the best dives I've done. The coral was okay, but the fish life was VERY abundant. Its only in about 30 feet of water, but the water is a bit rough as its right off a small island. We saw all sorts of wonderful life and our divemaster did a good job of pointing it out.
My boyfriend did a lot of research before choosing a dive operator and I would recommend them to you. We had our own private boat for 5 people. We paid $75 for our trip.
Hope that helps, let me know if you have other questions.