Coral reefs: fragile and under pressure

The Gulf of Thailand's coral reefs are living animals that grow only millimetres to centimetres per year, and they are under serious pressure. A 2024 heat-driven bleaching event affected reefs across the Gulf - reports cited up to 70% of reefs affected in some areas, with temporary closures of snorkelling sites to allow recovery. Scientific monitoring on Koh Tao (comparing 2016-2019, 2021, and 2022-2024) found coral health generally worsened after tourism resumed, with bleaching and White Syndrome disease the main problems and some coral families disappearing from surveyed sites. Reefs right off Samui's beaches are limited and already stressed; the better reefs at Koh Tao, Koh Nang Yuan, and Ang Thong see heavy visitor traffic - decades of boat traffic have left Ang Thong's reefs largely damaged, according to local guides. What visitors can do is simple and real: never touch, stand on, or collect coral (bleached coral can still be alive), control your fins and buoyancy, do not feed fish, and never buy coral or shell souvenirs.

Dates

Bleaching event documented 2024; ongoing monitoring

Highlights

• 2024 bleaching event affected reefs across the Gulf of Thailand
• Koh Tao study: coral health worsened 2022-2024 after tourism resumed
• Never touch, stand on, or collect coral - bleached coral can still be alive
• No coral or shell souvenirs

Local tips

• Wear a rash guard instead of heavy sunscreen layers when snorkelling
• If you stand up while snorkelling, find sand - never coral or rock with growth

Frequently asked questions

Are Koh Samui's reefs healthy?

Reefs near Samui's beaches are limited and stressed; nearby Koh Tao and Ang Thong reefs have documented bleaching and damage from warming seas and heavy tourism.

Is it OK to touch coral if it looks white and dead?

No. Bleached coral can still be alive, and touching or standing on it adds stress that can kill it.