Swimming in the South China Sea

The first time I encounter a Jellyfish was by being touched swimming in the South China Sea. It was of course extremely painful, but the first effect was the surprise, the shock of this very specific contact, like an powerful electrical soft whip from the left shoulder around the arm to the fingers. I saw the Jellyfish swimming away, big and elegant (more than me) I used the first thing I could think of once out of the water, a kind of cactus growing on Wei Zhou Dao, cut it and applied it on the burn. Very efficient, although I suffered partial insentivity for several days.The more important was not the burn, but the fact that there were plenty of Jellyfish in this area of various size, mostly quite big.Local people don't go to swim, may be because of the Jellyfish, who knows...