While there are plenty of in-water activities around St. Thomas, one of the best is at the Coral World Underwater Observatory. At this interactive park, which is great for families, visitors can see marine life rescue efforts, play with crustaceans or hang out by the beach. They can also swim with the star residents of the observatory, the sea lions. Rescued several years ago from certain death, today the sea lions are crowd favorites. In a special interactive session you can learn more about the ongoing research and interact with them in a special pool. This activity is safe for the sea lions and the mental stimulation is an important part of their daily schedule.