Ko Tachai

Island in Similan Islands Marine National Park

Twin Peaks at Ko Tachai is one of the best dive sites in the Similans, although strong currents mean it is generally reserved for experienced divers. Expect to see big fish: manta rays and leopard sharks, as well as turtles. Ko Tachai was closed to day trippers indefinitely in 2016 in response to growing environmental concerns; dive boats can still do dives here while remaining offshore.

Ko Tachai, along with Ko Bon, became part of the national park in 1998, when the park was expanded from its original nine islands.