I'll second Manpot's west end of Little Apple Bay is great. The area off of Bomba's (is it even there?) is also good when the swell is down and there's no surfing. Frenchman's Cay, go to the resort, park by the tennis courts, and enter thru their beach area, go to the left, you can go around the point and exit on their little pier. Keep in mind, the last time I was there was 2017 so the hurricane may have changed some things. The other end of the island, Long Bay East has great snorkeling at the west end. Josiah's Bay go out to the right and follow the coast. Back to west end, at Smugglers the reef right there is pretty beat, by there's still plenty of fish around on a good day. If you head towards the point to the right there's a lot of interesting areas. God, I miss Tortola. Can't wait to get back.