A couple of years ago, I spent 3 months there working on a project. I spent part of a day at Sand Castle as there is a nice beach and restaurant. I don't recall seeing anything else to do on the property. I stayed close to Christiansted and i like that end of the island. Might be fun and memorable to fly into STT and take the Seaborne sea plane to Christiansted unless Frederiksted is a done deal. In addition to what Swifty mentioned, a couple of interesting things I remember was a night kayak trip to see phosphorescence in water at Salt River Bay and the beer drinking hogs in the rain forest.