Koh Tachai is located between The Surin Islands, to its north, and The Similan Islands, to its south. Divers can get there by liveaboard diving boat, or day trip speedboat from Khao Lak in Phang Nga. Unlike Koh Bon, its neighbour a few kilometres to the south, there is a beach at Koh Tachai, but it is now closed to the public.
- Not for inexperienced divers
- Pros' Favourite
- Good chance of seeing Manta Rays and Whale Sharks
This Koh Tachai dive site is made up of two huge submerged plateaus on the south west corner of the island. Some divers and the dive centres they work for refer to these plateaus as The Twin Peaks. There's a small bay on the west side of the island which is where any night diving would take place, but this is not common. Basically, because it's quite far to travel back from in the dark. However, some liveaboard boats will stop off here for the night.
The sea conditions here at Koh Tachai are what make this dive site unsuitable for novice divers. Its location on the west side of the island make it exposed to the open sea. While this is excellent for the health and abundance of diverse marine life, including large filter feeders, it is the cause of medium to strong currents and choppy surface waves at times. January to May are the best times to come diving here, and it is closed for the rainy season due to the unpredictable conditions.
Once divers have descended down onto the plateaus, known as the ridge, there is a lot to look out for. Swimming carefully past the dozens of Gorgonian sea fans and coral bommies, divers can focus on all kinds of interesting critters and reef fish. However, other than budding macro photographers who have seen plenty of large fish in their time, most divers will, and should, be keen to keep an eye out for what they came to see. Manta Rays (Manta birostris) and Whale Sharks (Rhincodon typus) are common visitors to Koh Tachai and during the high season are spotted quite regularly. The thought of coming face to face with these huge filer-feeding cartilaginous fish receives mixed reactions. While some people may be unnecessarily worried about these harmless giants, others want to show their bravado or get a closer look. Approaching them or chasing them is not recommended because, although they're not scared by divers, they can feel unsettled or bothered and will swim away. This just spoils it for everyone involved, and may deter them from returning again soon.
Divers must not expect to be guaranteed large pelagic sharks and rays, and should be content with enjoying this dive site for it is. It's an impressive underwater oasis, filled with life in nooks and crannies all over the reef. Although it is not near the mainland, this doesn't stop marine reptiles from joining the party. It's possible to see the odd Hawksbill Turtle (Eretmochelys imbricata) or a Banded Sea Krait (Laticauda colubrina) near the surface. The turtles eat corals and the snakes hunt across the reef. Although their venom is more deadly than that of any land snake, these kraits can't and won't bite divers, and are neither scared of them nor aggressive towards them. Schools of Snapper (Lutjanidae) and Barracuda (Sphyraena) are interesting additions to the colour and movement here at Koh Tachai. There is also the possibility of coming across the large and slow-swimming Napoleon/Humphead Wrasse (Cheilinus undulates). Whale Sharks swim all day and night, but there are a couple of other species which can be seen resting here during the day. The Leopard Shark (Stegostoma fasciatum), which is actually called a Zebra Shark, and Nurse Sharks (Ginglymostoma cirratum) are sometimes seen at Koh Tachai.
Liveaboard diving boats come here throughout the high season, either as part of a Surin Islands or Similans cruise. However, one or two dive centres will do a short liveaboard trip to here and Koh Bon, but this is not common. For those who want to just visit Koh Tachai, and don't have the time or budget to get out to Richelieu Rock or The Similan Islands, a speedboat day trip is the best option. To find the best-value diving trips to Koh Tachai, click here and we promise to find a package to suit your budget, schedule and diving and non-diving needs.