An ounce of prevention re jellyfish stings; if you plan to dive, swim or
snorkel where jellyfish are present, why not wear a dive skin? It's a
full-length bathing suit that covers you from ankle to wrist. Looks like a
wetsuit, but is light stretchy nylon. It protects you from jellyfish and
other little stingers in the water. It was, I believe, developed for
Australian lifeguards as a protection against box jellies and "blue bottles."
Initially the lifeguards were wearing pantyhose, even on their arms!

Dive skins won't protect against sea urchin spines or stingrays or scorpion
fish, but neither would a 5 mm wetsuit. But dive skins do protect you from
the sun. You only have to put sunblock (I hate that slop!) on those parts
left uncovered. I had no base tan when I arrived in Exuma and I snorkeled for
an average of six hours a day, in the heat of the day. I kept cool as a
cucumber and didn't burn a bit. I bring two, one dries while I use the other.
They aren't any more expensive than most bathing suits. And worn underneath a
wetsuit a skin makes the process of putting the wetsuit on and off much
easier!