We did the Baths excursion here to Virgin Gorda -- a great way to spend 1/2 a day. Nice (but small) beach and fun crawling around the caves. Nice boat trip from Tortola to Virgin Gorda.
It poured rain (I guess that's why they call it a rain forest...) and there wasn't much to see at the top. Lots of mud and very slippery. It's a VERY steep hike (some on hands and knees) and I would wear hiking shoes if possible. Nice drive out to the volcano -- lots of nice views of old sugar plantations.
The snorkeling was SUPERB -- definitely do this. But this was a 3 1/2 hour excursion during which we spent only an hour in the water. Catamaran captain didn't seem to know what he was doing, as he took 5 passes at the pier before successfully docking. Also, they forgot to bring enough pairs of flippers for everyone on board. (Who does that??) So that's why we were delayed getting into the water. But once we were in, the snorkeling was great