Officials investigating the "red sea water" at Laem Phanwa Beach, Phuket, found a plankton bloom and warned tourists to avoid swimming as it could cause skin irritation.
On 15 November 2026, officials reported examining the sea water color change at Laem Phanwa Beach, Phuket, after spotting a reddish-brown stretch about 150 meters long along the shore. Preliminary findings indicated the cause was a bloom of phytoplankton genus Alexandrium sp. They warned the public and tourists against contacting or swimming in the affected area due to possible skin irritation.
On 14 November 2026, staff from the Marine and Coastal Resources Research and Development Center (MCRD) conducted on-site water quality tests at Laem Phanwa Beach, Phuket, after receiving reports of sea water turning reddish brown. The discoloration appeared as a long strip parallel to the coastline, approximately 150 meters in length.
Preliminary test results showed the cause was a bloom of phytoplankton genus Alexandrium sp., which altered the sea water's color.
Initial water quality measurements recorded temperatures between 32.4 and 32.9 degrees Celsius, salinity levels of 30–31 parts per thousand, pH values ranging from 8.24 to 8.36, and dissolved oxygen levels between 9.7 and 12.5 milligrams per liter. No effects on marine animals were detected during the inspection, while nutrient levels in the water are still being analyzed in the laboratory.
Authorities have requested the public and tourists to refrain from contacting or swimming in the discolored sea water area due to potential skin irritation. They will continue to closely monitor the situation and water quality to assess changes and potential impacts on the marine environment.