One of the main diving attractions in the BVI is "the wreck of the Rhone" a shipwreck just off the western most point of Salt Island in 20 to 80 feet of water. The RMS Rhone went down in 1867, but because it was one of the first iron sail/steamers, it is well preserved. If you only have time for one dive trip in the BVI, the RMS Rhone is it - it was voted #1 wreck in the Caribbean by Sport Diver Magazine.
There are convenient mooring balls directly above the wreck, from which you can easily see one portion of the Rhone while snorkeling from the surface. If you are a diver, as you descend to the Wreck a good portion of the ship's hull and many artifacts deposited in 1867 are still visible. You can swim through the still intact bow section as well as under the stern near the 15 ft propeller. You can also see the massive driveshaft and the engine box and gears. The wreck is also host to some great marine life - such as a giant green moray and several octopuses.More on Diving in the BVI.