Coki Beach, on the northeast shore of St. Thomas, is a good place for beginner snorkelers to see a variety of cool tropical fish.
The water is calm and clear and the fish can be seen literally as soon as you step in the water, with the greatest variety of fish and coral to be found at the edges of the cove, near the rocky outcroppings.
You can rent snorkel gear from a kiosk on the beach for only about $10 a day, or bring your own. There’s also a bar, a restaurant, and bathrooms. Don’t leave your valuables lying around unattended when you’re in the water though, because Coki is one of the few beaches on St. Thomas where thefts sometimes happen.