Hey Phil.
When I was down there a couple years ago my wife, daughter and I went out flyfishing for baby tarpon in Cancun bay. Awesome evening and fished into the night. Nothing fights like a tarpon.
The bay is the nursery for baby tarpon. By the way babies grow to 90 lbs in the bay. Rodman Hunter was the guy.
http://www.cancunsportfishing.com/flyfishing.html
If you go, ask him about the night fishing trip with a 5 year old when the saltwater croc attacked the boat trying to get a tarpon I had on.
SIO3