When we were in belize, we took an airboat tour and actually saw a school of manatees feeding and swimming around us - awesome mammals.Also in the airboat tour was a expanded version of the city tour in the sense we got to see both sides of their economy. In Roatan we went to the animal and monkey refuge. The monkeys actually come down and will sit on your shoulder or head etc, word of warning- keep anything shiny out of their reach or you will lose it!! The monkeys also love cola and they can actually twist open a bottle.
Hope this helps