In St Thomas 2 weeks ago we did a private jeep excursion with St Thomas Scuba and Snorkel. We were gone 5 hours, went to 2 snorkeling spots. the first was the sea turtle spot and while we saw 2 a weather front had kicked up a lot of sand so visibility was poor. So our driver pivoted and we went to another spot on the other side of the island which was over a reef and fabulous (though no turtles). We also went to an overlook over Magens Bay and went to a deserted beach (literally there were 3 other people there). It was great! We saw so much more and had more flexibility than the ship excursion. It was $400 for the 3 of us so not much more expensive than the snorkel excursions offered.