we just got back from our Caribbean trip. Here is what we did
Roatan: Dolphin Encounter & Tabyana Beach
Belize city: Jungle River Tubing & Mayan Ruins Site
It was relax but boring, and there is not much to see for the Mayan Ruins
Cozumel: Tulum Mayan Ruins
highly recommend, my husband rated this highlight of the trip. Don't forget your bathing suits.
Great Stirrup Cay: Snorkel & Parasailing
sign up early for the Parasailing, the seat are limited.
one more tip, since you are very into Snorkel (I guess), get your own gear from your local water sport store or costco, it will save you some money and time at the rental shop.