Plankton bloom transforms sea around Koh Larn into neon green

Plankton blooms occur when an abundance of sunlight and nutrients in a specific marine area makes micro-organisms so dense that they change the colour of the water around them.

Sorasak Thongbongpetch, secretary to the president of Koh Larn community, said plankton blooms happen two or three times during the early rainy season every year as freshwater flows into the sea. Seawater turns from translucent to green, but quickly returns to normal, he said.

The blooms have an odour caused by the mass death of plankton. Some people are allergic to plankton and it is best not to swim in a plankton bloom, Sorasak said. He advised swimming on other beaches on the island where the water remains translucent.