Green turtle diving in Koh Tao — it’s often the first underwater encounter that stays with people. Not the most dramatic on paper, perhaps. But when you see one for the first time at 6 metres, grazing quietly on a coral head as if you don’t exist, it’s something else entirely. Here’s everything we know about where to find them, when to look and how to behave.
Days per year
Typical depth
Max adult size
Life expectancy
The green turtle in Koh Tao — who is she?
The green turtle (Chelonia mydas) is one of seven existing sea turtle species — and the most common in Thai waters. Despite the name, its shell isn’t green. It’s the fat beneath the skin that takes on that colour from a diet of seagrass and algae. Adults can reach 1.5 metres and weigh up to 180 kilograms.
It’s a slow, methodical animal that spends most of its time grazing the bottom. Every 5 to 7 minutes or so, it surfaces to breathe — and that’s often when you see it best, suspended mid-water before diving back down. Green turtles can live up to 80 years. Some of the turtles you see in Koh Tao are probably older than you are.
Where to see green turtles diving in Koh Tao?
Green turtles are present on several sites around Koh Tao — not all of them, but the ones that offer the seagrass beds and sandy bottoms they need. Here are the sites where we see them most regularly:
When to see green turtles diving in Koh Tao?
The good news: any time of year. Unlike the whale shark, which migrates, the green turtle is sedentary — it stays in the same areas and returns regularly to the same sites. There is no “turtle season” in Koh Tao. Some individuals have been present on the same sites for years — our guides sometimes recognise them by scars or shell markings.
Turtles are more active in the morning, when they graze before resting in the afternoon. Morning departures from Koh Tao — our white boat leaves at 11am — give better chances of active sightings. That said, even a resting turtle on a coral head at 4 metres is a memorable encounter.
Do you need a specific level to see green turtles diving in Koh Tao?
No. It’s one of the few large marine animals accessible from your very first dive. Japanese Garden and Aow Leuk are at less than 10 metres depth — which is exactly the programme of a try scuba at The Divers Boat (first dive to 5 metres, second and third to 12 metres). In other words, you can see a green turtle on your very first dive.
For Open Water certified divers and above, all four sites mentioned above are accessible without restriction. Patience is the only real requirement — and a guide who knows where to look.
How to behave around a green turtle?
The green turtle is a protected species in Thailand — any contact or harassment is illegal. In practice, here’s how to behave to make the most of the encounter without disturbing it:
Is the green turtle endangered?
Yes. The green turtle is listed on the IUCN Red List as an Endangered species. Its main threats are the destruction of nesting beaches, accidental bycatch in fishing nets, ingestion of plastic waste it mistakes for jellyfish, and in some regions hunting for its meat and eggs.
In Thailand, it has full legal protection. Conservation programmes exist on several Gulf islands to protect nesting beaches. As divers, respecting distances and never touching these animals is the most direct contribution we can make.
We suggest the sites with the best chances based on your level — from your very first try scuba if it’s your first dive. Tell us your dates and we’ll take care of the rest.
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