Not far away from the hotel is a shop that rented bicycles, scuba equipment, and boats for hire for the day. The only option for the boat and captain was whether you wanted a cooler and ice or not; we went for the "whole boat" and ordered the cooler too. I think the boat was $200 for the day.
The captain was great -- he took us to several nice dive spots, and we did some scuba and some snorkeling. We saw the usual fish, but also sea turtles, which I had never seen, and lots of rays. The areas were not crowded at all. We took some good pictures, including one of me chasing a turtle!