Swimmers warned after plankton bloom colours Laem Phan Wa sea reddish-brown
Residents and tourists have been told not to touch or swim in the water off Laem Phan Wa after an Alexandrium plankton bloom formed a 150-metre reddish-brown strip along the shore.
Residents and tourists have been told not to touch or swim in the sea off Laem Phan Wa in Phuket after a plankton bloom formed a 150-metre reddish-brown strip along the shore on 14 November 2026.
Marine scientists from the Department of Marine and Coastal Resources’ Upper Andaman Sea research centre inspected the area on 15 November and traced the discolouration to a bloom of plant plankton from the genus Alexandrium. The centre said contact with the water could irritate the skin and advised people to avoid it until further notice while monitoring continues.
Initial readings recorded water temperatures of 32.4–32.9°C, dissolved oxygen levels of 9.7–12.5 milligrams per litre, salinity of 30–31 parts per thousand and a pH of 8.24–8.36. Scientists have so far found no harm to fish or other marine life and have sent samples to a laboratory for detailed testing of nutrient levels.
The warning applies to the water directly in front of Laem Phan Wa beach, a cape on Phuket’s south-east coast in Mueang Phuket district. It does not cover the island’s main west-coast beaches.
