Koh Tachai is an island with beautiful white sandy beaches, located 20 km north of Koh Bon, and offers two popular dive spots, namely the Tachai Pinnacles and the Eastern Reef.
Also known as Twin Peaks because of its pair of submerged pinnacles, the Tachai Pinnacle is located about 500 metres south of Koh Tachai. At a depth of 12 metres, the larger southern pinnacle is dome-shaped with huge boulders surrounding it and ends in a sandy seabed about 45 metres deep.
50 metres away from the southern pinnacle is the northern pinnacle. The smaller northern pinnacle is formed by a cluster of rocks and covered with large corals and sea fans, just like the southern pinnacle.
Manta rays and whale sharks can be seen feeding on plankton around the pinnacles. Sharks including blacktip, whitetip and leopard sharks and schools of barracuda, batfish, snappers, trevally and triggerfish are often seen. Try to look out for interesting marine life such as the camouflaged frogfish, and the colorful mantis shrimp, which can be quite difficult to spot.
The Tachai Pinnacle is notorious for strong curents, especially during the full and new moon. During such strong currents, divers will not be able to dive around the entire formation and can only do so in the areas sheltered from these currents.
The Tachai Eastern Reef is also known as Leopard Shark Reef. As both names suggest, the Reef is situated throughout the eastern side of the island and Leopard Sharks are commonly seen resting in the sandy portions of the reef. The southern part of the Reef slopes gently to a steep drop-off down to a depth of 30 metres.
Hard corals such as brain, fire and staghorn corals cover much of the Reef. Cuttlefish, lionfish including the Twin-spotted or Fu Man Chu Lionfish, moray eels, nudibranch, parrotfish, pufferfish and large stingrays provide great subjects for underwater photographers. Night diving presents opportunities to see various crustacean species such as crabs, lobsters and shrimp.