In Grand Cayman I would recommend the Wave Runner Tour to Stingray City and Rum Point
is was incredible!!!! It leaves from a resort, nice resort, beach was so-so but the tour was incredible and Rum point was beautiful!
In Belize, I highly recommend X-Stream Cave Tubing
we've gone with them two times, once just cave tubing, and we loved it so much we returned and did the combination with zipline too. Great company!!!
In Cozumel I can't recommend a scuba company as we did the ATV's
another great tour!