National Park on St. John
Take the ferry from St. Thomas to St. John....when you dock in Cruz Bay, walk around to the left to the National Park Service office/visitor center. You can get a trail map and do some great hiking....with great views....FREE! Of course, you'll want to head to famous Trunk Bay, too.....fee.
"Iguana Welcome Committee"
Just off the ship as you walk towards the ground transportation, there are many, many big iguanas on the rocks of the beach. Very cool!
When we first got to Magens Bay, we were almost the only ones there. By lunchtime it was like Venice Beach. Get there early! Also, be prepared to pay at least $8-10 per person to get there and then the same amount to get back or to the shopping area. Another $5 back to the ship. Lots of $$$ if you have a large party.
The only areas (Magen's Bay, shopping area) we were able to see in the time that we had were very crowded and did not live up to our expectations of the Virgin Islands. It was nice but maybe better 20 to 30 years ago. Lots of building and construction. Almost like Honolulu. I guess you can say that about most any of these tourist areas but this port felt just way too much like a tourist trap.
St. Thomas can be a great place to visit, if you enjoy shopping and don't mind crowded beaches. I highly recommend a visit to Magen's Bay and a night out in Frenchtown. Be careful, as crime can be pretty bad - definitely don't walk around town or remote beaches at night. If you can, take a day sail out to somewhere for snorkelling (Buck Island is a good spot) or charter a boat for fishing. It's also a short ferry ride to St. John or the British Virgin Islands.