- Fish
- Pterocaesio chrysozonaScientific Name
- Least ConcernIUCN Threatened Status
Green Sea Turtle
Green sea turtles are among the most commonly encountered sea turtles around Koh Tao. Divers and snorkelers frequently spot them feeding on seagrass, resting beneath coral formations, or cruising slowly over shallow reefs.
Endangered
Overview
The green sea turtle is a large, weighty sea turtle with a wide, smooth carapace, or shell. It inhabits tropical and subtropical coastal waters around the world and has been observed clambering onto land to sunbathe.
It is named not for the color of its shell, which is normally brown or olive depending on its habitat, but for the greenish color of its skin. There are two types of green turtles—scientists are currently debating whether they are subspecies or separate species—including the Atlantic green turtle, normally found off the shores of Europe and North America, and the Eastern Pacific green turtle, which has been found in coastal waters from Alaska to Chile.
Weighing up to 700 pounds green turtles are among the largest sea turtles in the world. Their proportionally small head, which is nonretractable, extends from a heart-shaped carapace that measures up to 5 feet. Males are slightly larger than females and have a longer tail. Both have flippers that resemble paddles, which make them powerful and graceful swimmers.
Individual turtles can be identified by their unique facial scale patterns — the Koh Tao Turtles Facebook group coordinates sightings and ID records for the island.
Identification
A green sea turtle resting in a coral rubble field in Shark Bay on Koh Tao.
Logan Brown
Two green sea turtles interacting in shallow water in Shark Bay at the southern end of Koh Tao.
Logan Brown
Long paddle-like front flippers — allows them to move effortlessly at cruising speed with minimal visible effort.
Logan Brown
Conservation Notes
Maintain at least 3 metres distance. Never touch, chase, or block movement. Green turtles are protected under Thai law — violations carry serious fines. If a turtle approaches you, stay still and let it pass.
Green Sea Turtle Facts
Where to find them
At White Rock, look for turtles on the seagrass patches along the western side — usually between 8 and 12 metres. They’re most active in the morning. At Tanote Bay, check the sandy patches between coral heads on the north side. Stay low, move slowly, and they’ll often sit with you for several minutes.
Frequently Asked Questions
Green sea turtles are regularly seen at White Rock, Twins, Japanese Gardens, Shark Island, and Aow Leuk. Sightings are possible throughout the year. You are most likely to see them very shallow either snorkeling or near the end of your dive.
No. Divers should never touch, chase, or block the movement of marine life. Giving turtles space helps protect their natural behavior and reduces stress.
Adult green sea turtles are herbivores that feed primarily on seagrass and algae. Juveniles eat a more varied diet including invertebrates. Their plant-based diet is what gives their skin and fat the greenish tint that gives the species its name.
Yes. Green sea turtles are classified as Endangered on the IUCN Red List. Major threats include hunting, egg harvesting, habitat loss, fishing bycatch, and boat strikes. They are fully protected under Thai law.
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