One blight on divers’ lives is “seabather’s eruption.” On a recent outing I accidentally swam through a swarm of Thimble Jellyfish. Jumping into the water to cool off with my wetsuit half open, some of the larvae of the Thimble Jellyfish must have gotten inside my wetsuit. So when I put it back on they became trapped.
The larvae don’t cause any problems when they are wet and in seawater. But once they come out of the water they die and the larvae discharge their nematocysts when crushed, dried out or exposed to fresh water. The nematocysts cause small round spots from as small as 1mm up to 1.5cm. They are very itchy and can take from a few days to a couple of weeks to disappear.
The best way to prevent them is to rinse yourself with seawater after swiftly removing the wet clothing. The contaminated clothing should be washed as soon as possible. If you do get caught with them, do not try to scratch the spots and use a cortisone solution to ease the itching.
I hope you don’t get caught with them. I can tell you that the itching can be quite unbearable. Plus it looks like I am now a teenager covered in acne.