Been there twice, and did the catamaran both times. Absolutley the best thing you'll do there. Dolphins, sites, etc. Its a great thing...but not necessarily for the snorkling, which will be good. Snorkling will be totally different than anything you 'll see on the beach. Unless you're more secluded, all the snorkling off the typical tourist beaches is going to be pretty average.

I believe we did Captain Andy's last time and it was a good one.

HIGHLY RECOMMEND YOU DO IT!!