Hi - you might want to search these boards a little further back. You'll find tons of info on St Thomas and St Martin.
My personal suggestions:
If either of you enjoy big airplanes landing at a close distance over a beach, then go to Maho Beach. www.sunsetbeachbar.com
has pictures. The big planes land after lunch. Air France has a nonstop from Paris, and we've seen American -757s land, Continental, etc. This is free, and there is a beach bar (outdoor, picnic tables) right there. A "bar" is not really the name - it is somewhere your son could grab a soda, but I'm guessing he's want to be right in the middle of the action in the middle of the landing pattern.
Or, for about $80 each, go on the America's Cup. Your ship will most likely have it as an excursion. I have friends who have done that - some are experienced sailors and even enjoyed it.
Be adventureous and take a ferry to St John. (Notice St John is SINGULAR... so many people refer to it as St Johns... plural... which is actually a city on Antigua). You can take a cab from ship to Red Hook for about $5 each and then ferry for $3 each to St John. At Cruz Bay (on St John) cabs are plentiful and can get you to Trunk Bay for about $4 each.
There is beach after beach on St John. Snorkeling is safe as long as you don't venture too far out. Also, each beach is unique - some are known for coral, others for colorful fish, some for underwater trail, others for facilities. Depends on what your son is after. We paid about $30 for our own snorkel equipment that has turned out to be a terrific investment.
We married there this past March on Hawksnest Beach. Trunk Bay costs $4 per person, but the next beach over is Cinnamon ... and free. There is a 40+ year old plane wreck about 20 yards off the beach that one can snorkel over. My husband and I love that. (A terrific book you can purchase is by Pam Gaffin titled "St John Feet Fins & Four Wheel Drive - I bought mine over the internet)
Past threads on here talk about Trunk Bay and Cinnamon Bay, as well as transportation. Also, a great website about the US Virgin Islands is www.vinow.com
It shows taxi rates, ferry schedules, etc. We took a land vacation to St John last November staying in the Concordia ecotents (www.maho.org
) and loved it. We are currently planning a return trip back.
I'm not sure (don't remember) but I think there may have been parasailing at Trunk Bay. (???) I do believe there is SNUBA though. We did that in Aruba and thoroughly enjoyed it. It's a cross between SCUBA and snorkeling. http://www.snuba.com/
St John will definitely give you the feeling of Robinson Crusoe (or however you say it). Like you are on an adventure on a Caribbean island!!
Seriously, though, do some searches on these boards. You'll probably be amazed at what has been posted already about these areas. Might give you some ideas (such as Coral World on St Thomas, etc)
~ Mandy in Dallas