I've read the postings on this subject and I feel I have to share this with you, we went to San Pedro in March, did the Hol Chan and shark Ray Ally Snorkling tour, when I was snorkling Hol Chan, I got STUNG, I knew it immediatley and got a leg cramp right aftrwards, when I got back to the boat it immediatly swelled up , it was on my thigh. I put an ice bag on it, along with some "cortaid" I had brought along.
I thought it was a jellyfish, but I'm starting to wonder, when we got back to the states I had to see a Doctor, he gave me cotazone pills to relieve the pain, and lotion to relieve the itch, I still have a mark that is about 3X2 iches wide...
Not sure what it was, but it hit hard, and I remember seeing some sea grass just prior to being stung.. OUCH..
I will return to Hol Chan, but will wear a wet suit next time!
You can still see where I was stung, it's still bumpy but it dosn't hurt anymore.
I thought maybe sea nettles? Our guide said it was a jelly fish, but Man, it must have was a big one then, and it hurt instantly.