I agree with Willyg -- if it's too windy to fish, it's likely too windy and choppy to snorkel comfortably.
You're coming at one of the windiest times of the year, the spring, and on quite a few days the chop may be too much for comfort. Once in a while we get comments from folks who have visited that "we didn't know it would be so windy on some days that we couldn't go out on the wate -- nobody told us." Small craft warnings are surprisingly common off the coast of Belize.
Belize First Magazine http://www.turq.com/belizefirst/