I have never been snorkeling but want to give it a try. Will be stopping in Labadee (is it available there? The RCI website doesn't show it as an excursion - the only plans I have there are parasailing and beachin'), Ocho Rios (doing Dunn River and Jimmy Buffett so prolly no snorkeling time here), Georgetown (horseback riding - should have snorkel room), & Cozumel (Dolphin Discovery - might have snowkel time).
Deb, snorkeling in Cozumel is great, plan time either before or after your dolphin swim to snorkel around the park. Caymen has some really neat snorkeling around old shipwrecks, lots of dive shops on the main street that offer snorkel tours, the snorkeling associated with Sting Ray City isn't all that great. Snorkeling in Jamacia- don't bother, all i got from snorkeling in Jamacia was coral bruises & cuts, the coral is very sharp and just jutts right up at you if you aren't careful. My legs and arms were a mess.
You absolutely MUST reserve a Stingray City Tour with Captain Bryan's!! We did it in Grand Cayman last Thursday and it was incredibly amazing! The crew is awesome, the catamaran is awesome, the stingrays are awesome...what a fabulous experience!
When you get off the ship, turn left and walk about 4 blocks and captain Bryan's is on the right side of the street next to a bakery (BTW, bakery has great pastries).