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Koh Tachai is an island that has been part of the Similan National Park since 1998. It is located 20 kilometres north of Koh Bon, and is the last island north before the Surin islands.

Similar to the other Similan Islands, its characteristics are an abundant jungle surrounded by an immaculate white sandy beach. Loved by all, gorgeous and perfectly protected on one of its sides, Koh Tachai delights divers and snorkelers alike.

There are 3 diving sites and numerous bathing spots in Koh Tachai.



The South-East reef

Accessible to divers of all levels, the reef forms a wide plateau with a depth not more than 10 metres, followed by a short reef drop that ends on a flat and sandy bottom at around 30 metres.

The plateau is more interesting for snorkelers, who will enjoy angel fish, butterflyfish and dozens of bluespotted cornetfish. Divers will quickly go down the reef drop in search of red lionfish, scorpionfish, nudibranchs, octopuses, giant morays, zebra morays and tankfish. It is not rare to be able to follow turtles swimming around the area! Sometimes, Kulh’s stingrays and marbled rays hide in the sandy bottom, as well as bluespotted ribbontail rays.

And if you are really lucky, you might even meet the leopard shark!



Did you know?

In Thailand, we try to index the different kinds of sharks we meet during the season, especially whale sharks and leopard sharks. So if you have pictures, please help us in our indexing by sending them to us. Also, if it is a shark that has never been identified before, it will be given your name!


The South-West reef of the island

Accessible to all divers, this reef is made up of big blocks of granite going down from 9 to 15 metres, followed by a gentle slope sprinkled with coral rocks down to a depth of 30 metres.

You can see turtles, giant morays, marbled groupers, bar jacks of all sizes and a multitude of reef fish.

Minimum/maximum depth: 5 to 25-30 metres.
Current: low to strong depending on the tide, but possibility of drifting easily.
Level: all levels. Beginners are welcome.


The Pinnacle of Tachai

A few kilometres down South from the island of Tachai is an extraordinary pinnacle, a truly hidden treasure where you can often be part of unforgettable encounters…

Impossible to see from the surface, the top of this pinnacle, also called “dome”, is located between 12 and 15 metres. Its natural exposition generally makes it face very strong currents. This is the reason why this site is only accessible to experienced divers.

The various currents encountered in Koh Tachai vary during full and new moons. Currents brew plenty of food, plankton and zooplankton for marine animals. This is the reason why we will meet regularly with manta rays, whale sharks, shoals of thousands of barracuda and bar jacks of more than one metre. Life on this site is extraordinary.



The top of the dome starts at 12 metres with a granite block that quickly drops onto a plateau covered with rocks and soft coral at around 15 metres. You can find moray eels, magnificent sea fans, nudibranchs, trumpet fishes, etc.

The rest of the site surrounds the plateau and can go down up to 30-35 metres. It is easier to protect yourself from the stream if you stay below 18-20 metres or by finding shelter around blocks of granitic rocks. In all cases, follow your guide!

This is a beautiful site with giant sea fans, hard and soft corals of all colours and a diversified wildlife in perpetual motion. Silver bar jacks intermingle with black bar jacks in unique hunting waltzes, while different species of barracuda twirl together in spirals over our heads.


Koh Tachai is undoubtedly the favourite site for the professionals in the region, both for its wild and unspoiled beauty as for its extraordinary encounters. However, it remains highly recommended that inexperienced divers unaccustomed to diving with different currents do not dive on this site.



A hundred metres north of the dome lays another pinnacle even wilder than the main one, but only a few guides go there because of its remoteness and difficult conditions of access due to the current. If you are lucky enough to visit this little treasure one day, you will never dive the same way! But shhh, this is another story…


Minimum/maximum depth: 12-14 metres to 35-40 metres.
Current: moderate to strong.
Level: not recommended for beginners. Experienced divers only.



Desire to dive ?

Come and join Globe-Divers for 2 beautiful dives at Koh Tachai starting from 5300 baths (moreless 120€).

Book your dives from now using the following questionnaire!