Check out this place:
http://www.eagleraydivers.com
We did a snorkeling trip with them and had a FANTASTIC trip!Small boat (max 10 I think)Great crew, very nice to deal with. We did the 3 reef trip which includes a nice lunch at a dock side resturant. The price was very good (about half what
DCL tour was). You will need a cab to get to them, but we had no problem getting a cab, who then met us when we returned for our trip back to the ship.
We had a group of 10 (6 adults, 4 kids) and we all agreed it was the best trip of the cruise.
I'd be happy to answer any questions.