There is a place that breeds Sea turtles in Cayman as well. It was a pleasent experience. They have a pool there that is connected to the shark pool that you can swim in. I would recomend a long shower after that swim, however.
While in Cayman, make sure to try conch soup and Blackbeards rum cake.
When you get to Cozumel ask the locals what is the best place to eat Lion Fish. I went to some backyard restaurant out there and the fish was amazing. Wish I would have kept the address.