On the south side of St John you can get away from other boats and still enjoy all the wonders of this fantastic island. For example, in Reef Bay you can explore the last active sugar factory on the island. In fact this factory invested in steam powered equipment, which is very cool to see. Most people visit the Annaberg factory, but this factory is more intact and helps you see the process better.
Plus up on the ceiling you will find a dozen or so bats hanging upside down and sleeping. After you are done exploring the factory you can hike an easy mile to the petraglyphs or play on a fairly secluded beach.