We booked the Catamaran Ultimate Sea Sun & Fun. It was a long excursion that ended too soon. 3 snorkel stops and a lobster lunch on a secluded (private) beach. The snorkeling was good, the lobster was huge.
This may have been the best excursion we've ever done.
We took a taxi to Saphire beach. It was a little more crowded than I was expecting. That may have been my fault as we got a late start and didn't get there till 11:30am. The beach and water was spectacular. The beach service was slow, but we weren't in a hurry.