by far the best snorkeling is out at the reef....
its not expensive to get out there, and well worth it.... I'm sure Tim can book the cave tubing for you, or you can contact Ian Anderson at
[email protected]..
info on their trips is at: //AmbergrisCaye.com/pages/town/cavesbranch.html
more at: //AmbergrisCaye.com/pages/town/cavetubing.html
I'd wait to book the trip to the ruins til you get there, or at least til right before you go, to match your schedule with the tours. I'd get ahold of them a couple days before you leave to find out what days they are going, and let them know your group will be with them on a certain day so they can plan for it too...