St. Thomas is a small mountainous island with spectacular views, amazing marine life, and lots of history, so it's no wonder that the best attractions on the island highlight these natural strengths.
Coral World, for example, is a mini-marine park that consistently ranks as one of the Caribbean's most popular attractions. The underwater observatory, stingray-feeding pool, shark tank, and sea lion show highlight the natural marine wonders of the Caribbean. The park is especially popular with the younger set.
For the best views on the island, the Skyride to Paradise Point is a top choice. First you experience the thrill of riding a cable car up a steep mountain peak, then you are treated to incredible 180-degree views over Charlotte Amalie Harbor, Water Island and Hassel Island.
Another spectacular view can be had at Mountain Top, a hilltop gift shop and observatory, which reopened in 2011 after a devastating fire in 2009. Here the views stretch out toward St. John, Jost Van Dyke, and Tortola. The gift shop has far superior items to many other locations on the island, and the famous banana daiquiris can't be beat. Similar views can also be seen from Drake's Seat, minus the gifts and drinks!
The best historical attractions on St. Thomas include Fort Christian (built in 1672), which is just to the east of downtown, and the famous 99 Steps which lead up to the Danish-era Blackbeard's Castle. Take a self-guided tour and you'll get a good feel for the history all around.
And last but not least are the beaches. Magens Bay Beach is the most famous on the island, and some say the whole Caribbean. Its incredible white sand, calm turquoise water, swaying palms and isolation from the "real world" make it a must-see stop on any itinerary of St. Thomas.