We really loved the Snuba, even though my husband and I didn't stay down long. Our instructor was very helpful and our adult kids had a great time. Coral World itself was underwhelming. Did like the stingray display.
Beware of the taxi/tour people. They ONLY want you to take tours. Getting a private taxi was insanely difficult and time consuming. They literally herded us to the taxi area and it was controlled chaos. Hated it. Was told it would cost $300 to get a private taxi to go to Paradise Point and Drake's seat. Yeah, right. If you don't want to jump on one of their multi-person taxis and take a tour or go to downtown forget it.
Getting off the ship at St. Thomas went the worst of any port, with huge long lines in the stairwells with crowding and waiting at a peek. Other ports went much more smoothly.
Since we aren't beach people we needed something to do. The beach here is gorgeous, but the island is covered with rocks, scraggly bushes, and desolate looking living areas. On the dune buggy tour you have to follow in a close-knit straight line all around the area. It wasn't really a dune buggy either, but a two person ATV with a cage. It beat sitting on the beach for hours, but wasn't our favorite tour.