I took my family to the beach, for 4 days last week, and we encountered some problems. As soon as I got into the water, I noticed a stinging sensation. Similar to fire ants, or stinging nettles. It wasn't that bad for me, but the kids were complaining to their mom about it. I got my mask and snorkel out, and tried to see what it was, that was stinging us, but couldn't see anything. But later around sunset we did spot a red jelly fish, swim right up to the beach. I noticed a few small blisters on my arm. No big deal... But my son, that isn't quite 2 years old yet, had several nasty red welts, that he couldn't stop scratching. We rubbed some calamansi on it, and after the initial shock, he calmed down and stopped scratching. Anyone know what unseen critter could have been doing the stinging?