I agree - I think Marina Cay is very risky. You also have to get yourself all the way to Trellis Bay from the cruise dock - about a 30 minute cab ride - and figure in the time to get back. You are much better off getting a day charter out of RoadTown -- as for Peter Island, it is definitely not a cruise ship day spot. As far as I know, their ferry is for registered guests only. You can spend the day there if you are anchored on your own boat in Deadman's Bay -- but there is no transportation there for non-guests other than the ferry that brings workers over.