In St. Thomas I went snorkeling at Turtle Cove. It was awesome. There are turtles in the water and they are not afraid of humans. You leave them alone and they leave you alone. I saw one and maneuvered myself above it and was taking pictures and then it swam directly up towards me! That was my first time snorkeling and I really enjoyed it.
Then I returned to the ship for lunch. After lunch, I went to the Butterfly Farm and then the Sky Ride. The Butterfly Farm and Sky Ride were done at my leisure. I recommend all of the above.
There is also shopping right by the port. I went in a couple shops before I had to be back on the ship.
I booked via the cruise line.