On St. Thomas, Coki Beach is a shore dive just a few minutes north (east?) of Red Hook. But it's pretty marginal, shallow and somewhat sparse. Instead I'd do a boat to the cays with either Red Hook or Dive In - they're just 20 mns. or less out.
St. John is easy, 15-20mins. from Red Hook on the East End - slightly longer from Charlotte Amalie. There's several car ferries from Red Hook - I think they stop around 6PM. People ferries from Charlotte Amalie run till Midnight. I was with some friends so I don't know about getting around Cruz Bay or other parts of St. John once there. Chris Sawyer's just relocated there after years on St. Thomas. I think Cruz Bay Watersports is still there also.
Lots of crazy drivers on St. Thomas...
If you're feeling
adventurous, Tortola and diving the Rhone is possible with the right timing. It's the signature BVI wreck.
The ferry from Red Hook is either 35 or 50 minutes into Roadtown Tortola, some of the ferries into the West End
may be even shorter. Ferries leave as early as 8AM some days with the last returns around 5-6PM on the weekends.
The Rhone is about 30-45mins. from Roadtown - I'm guessing - been to Roadtown and dove the Rhone but never both in the same day - so it should be possible to do a double and still get back in time for one of the later afternoon ferries. If I had to guess, I'd say the whole trip out and back from Tortola would be about 4 hrs. Note that Tortola is a really long island so pick your diveop according to proximity to where the ferry drops you - it's a long cab ride between the West End and Roadtown.
Most dives on the Rhone are a double as the front and back are far enough apart that they move between moorings. It's a great wreck dive, it was a huge ship - a lot of it is still intact. There's a swimthrough in the front - the Deep was filmed there - and the back is a big jumble of ship and machinery back to a huge prop that has a swimthrough between it and the 2 story rudder. Not very deep either I think the bow is 85' to the sand and the stern is less.
Saturday is the optimal day to do this as the last ferries are at 5:15/5:45 depending on your point of origin. Other days in the week it's much earlier.
You also need to clear customs both ways so plan that into your schedule. And bring your
passport. I'm sure one of the BVI diveops know how to do this. You are going to burn a day for two dives though so that might not meet with your plans to squeeze in as much diving as possible - we do that also. For the Rhone, I would honestly make an exception, I dislike wreck diving but thought it was the best I've ever done.
One last gotcha - the ferry schedules are sometimes hit/miss. We were going to do an overnight to St. Croix but the ferry went out of business a few months before our trip. And now it's back. Even though it's only a 90min. ride there's not enough ferries for you to consider it as a day trip.
A couple of useful links to help plan:
Virgin Islands Ferry Schedule
Welcome to BVIScuba
