When is the best time of the year to go snorkeling in Key West Florida?

AnswerAny activity is good three hundred sixty-five days a year in Key West. The phrase 'it's all good' describes Key West because literaly it is all better in the Keys. But if you want to see specific wildlife, well I don't really know the seasonal migration routes of the local fish but you could look on The Animal Planets web site under their ocean series icon and see if it's listed or if there is a link. Not meaning to be a smart-aleck but there is no such thing as a bad day in the Keys.

avoid shiny objects on you like dive watches as they attract Barracuda

Stay warm in winterIn winter the water is nice and warm but still cool enough that snorkeling for any length of time will get you shivering. Especially on the key's reef trips which tend to be away from shore. In winter I would recommend a neoprene shirt which is like a wetsuit top but less than 1mm thick. Mine is 1/4mm and short-sleeved). It packs well, looks great, and keeps you warm enought that people will ask to borrow it. There are lycra/spandex shirts that look like neoprene shirts, and claim to be snorkeling shirts, but don't keep you as warm. They are really just undershirts for wetsuits.