Storm-fed plankton bloom seen around Koh Lan

PATTAYA — The sea around Koh Lan, a popular island destination just off Pattaya in Chon Buri province, turned green on Wednesday, surprising some tourists unfamiliar with the phenomenon of a plankton bloom following heavy rainfall.

The unusual sight appeared after several days of heavy rain, strong winds and unstable weather in Pattaya and surrounding areas.

Increased freshwater runoff into the sea carries sediment and nutrients that can fuel the rapid growth of plankton, changing the colour of seawater depending on the type and concentration of organisms present.

Beachfront on Wednesday at Koh Lan. (Photo: Amporn Saengkaew)

According to the Department of Marine and Coastal Resources, seawater discolouration can occur when plankton populations increase rapidly. Nutrient levels, ocean currents, water temperature and weather conditions all influence the phenomenon, which is more likely when runoff increases during the rainy season.

Plankton blooms are a natural phenomenon, and the water can gradually return to its normal colour as conditions change and plankton levels decline.