When I was a tad, I was diving and swimming off the wharf at Cap de Cassie near Shediac, New Brunswick, Canada. I was just about to take another running flying leap when a big commotion began. A man was pulled up onto the wharf with almost the entire left side of his body badly "burned" from diving into what is locally called a Spanish Man-o'-War. I had had lot of jellyfish stings but never even knew these big buggers existed. Never dove into salt water since.