Authorities are warning beachgoers to watch out for jellyfish this summer.

The National Fisheries Research and Development Institute announced that the poisonous creatures, including a giant species called Nomura's jellyfish, have been found in swarms along waters off the western and southeastern coasts.

The deadly Nomura's jellyfish can grow up to 2 m in diameter and weigh as much as 200 kg, and their numbers are expected to rise in the coming weeks.

Experts advise against any bare-skin contact with jellyfish, even dead or dying ones as they can still sting when touched.