I strongly agree about Mexico Rocks vs Hol Chan/Shark Ray, Black Orchid and the other recommendations.
In addition, you MUST check out "The Truck Stop" for food, concerts, movie night, cornhole tournaments, open pit pig roasts and more!
We rent out kayaks, and have a 'floating island' safely anchored out of the boat lanes, so you can paddle out, hang out, and snorkel to your hearts content.
A day of sailing on the Rum Punch II, is what we consider to be our favourite day on the island. (He will also take you to Caye Caulker, plus Hol Chan and Shark Ray.) Truly an amazing day no matter where you go with Captain George!
A guided tour on the back side of the island up to Bacalar Chico (and watching the Mexican Coast Guard patrolling the waters is always exciting). Plus, you'll stop at our other tie for a trip on the Rum Punch II, which is a stop at Tranquility Bay.
(I think I'm going to have to take a few days off just to do all of these again myself!!)
Have a blast!