You do not need to go on an excursion to go snorkelling in St Thomas. There is decent snorkelling right off the beach at Saphire Beach or Coki Beach and all facilities you need are available as well.
Trunk Bay vs. Buck Island. You can get to Trunk Bay on your own . Cab to Red Hook Ferry, ferry to St John, Cab to Trunk Bay. Beach is nice, snorkelling is ok. There are little underwater markers that mark a snorkel "trail" that make snorkelling fun.
Buck Island is not the very famous underwater park named Buck Island which is off St Croix. This Buck Island is about 4 miles offshore from Charlottle Amoille. You will need to take an excursion to get there. The boat ride to and from is half the fun to me. Boats anchor in one of two coves. One has a sandy beach and some half dead coral along the shore and attracts fish and an occasional turtle, the other has a rocky shoreline but has the wreck of an old ferry boat sitting in about 30 feet of water. Boats will anchor in one cove or the other, neither is really preferable. You can't go ashore on Buck Island as it is a protected preserve.
I like going to Dawn Beach in St Martin. Less crowded than Orient Beach and just enough in the way of facilities, beach ,snorkelling etc to keep me happy.
I agree Dawn Beach was a good snorkeling spot,. Thet have all the equipement you need there. We went on an excursion in St. Thomas and were very Disappointed. It was offered through Princess. Make sure the seas are not rough when you plan to go or it will be a wasted trip.
St. Thomas you can do on your own no excursion needed. Have been hearing that the snorkel trail at Trunk Bay is dying from overuse. We liked the snorkeling at Cinnamon Bay (next door to trunk) there is a small Cay just off shore with a reef around it, pretty good snorkeling here.
St. Maarten - for good snorkeling i would suggest booking a ships tour over to Pineal Island.
We just returned from a stop in St.Thomas and had made arrangements for a day aboard the Winifred (www.sailwinifred.com) on suggestion from a posting on this site. Even though our day was a bit overcast we had a fantastic day snorkeling off the coast of St.Johns and across the bay. The beaches we anchored off of were beautiful, and nearly ours alone...the snorkeling was fantastic, lots of coral beds, rays, star-fish, reef fish, even a Moray, all observed from a respectful distance! The water clear, one spot we worked was over 55ft deep and it was like looking in an aquarium!
I heartedly recommend a day aboard the Winifred and would be glad to exchange info if needed....we're already planning on a return trip!!
Agree with the advice to take a day sail from St Thomas to St John. There are quite a few companies, and from the reviews I've read they all do a super job.
I've used Interline Sail- they offer both full and half day sails. Check them out at www.interlinesail.com
The snorkeling at this cruise stop is the very best- leave the shopping for another island.
Last March we had a great excursion with the ship(Celeb) to trunk Bay . Very convenient as the boat over was a few steps from the ship & then you take a tram right to the Park. . Trip to St John's was very choppy but the snorkeling on the trail was amazing.. we had plenty of time to snorkel & get lunch at a snack stand...everything at the Park was clean & well kept. guess it depends on alot of factors--what you want, the weather & sea conditions.