
Sizeable red Chrysaora jellyfish have been sighted in large numbers off the shores of Koh Hong, Koh Laoding and Koh Phakbia.
The warning signs have gone up around Than Boke Khoranee Marine Park, park chief Weerasak Sisatchang said on Tuesday.
Also known as sea nettles, Chrysaora can inject a venom designed to kill small prey but which is not lethal to humans. It can, however, result in a painful rash that lasts about 20 minutes.