Halfway between the Surin Islands and the Similan Islands, Koh Tachai is a small uninhabited island.
The main features of diving here are its submerged pinnacles, large boulders, and excellent wildlife. The top of the reef is built with excellent specimens of hard coral while deeper parts are known to have many boulders, seamounts and sea fans. It’s a good place to spot white tip reef sharks, nurse sharks, manta rays and the king of all marine animals, the whale shark. Other more common species such as large schools of barracuda, Napoleon wrasses, yellow-backed fusiliers, and bannerfish can be found in huge numbers.
The Koh Tachai Pinnacle is often referred to as Twin Peaks or The Dome because the site does have of 2 pinnacles with a huge dome-like granite boulder as the central feature of the dive site. Large boulders are spread all around this central rock creating swim-throughs, channels and coral plateaus rich in life.
Twin Peaks
“Twin Peaks” Koh Tachai southern pinnacle is marked by two mooring buoys; one mooring line goes down to around 15m, the other to 33m. It is advised to use one of these mooring lines for descent and keep close to the rocks since currents can be rather strong here. At a depth of 12 meters you will encounter the top of this pinnacle, which really looks like a wide flat plain with bush and mountain coral encircled with boulders.
Frogfish
Here camouflaged in the bush coral frogfish hide away from obvious sight, although even more experienced diver finds it still difficult to locate them. Descending further you come across several flat areas varying in depths, stepping down to a sandy bottom at 30m and deeper where Jenkins’ rays, as well as whitetip and blacktip reef sharks, rest in the sand. Which direction to spiral up the contours of the rocks, really depends upon the current. In fact, the stronger current brings a constant supply of nutrients to the site which benefits many species of fish and coral. In the west section, you will find large boulders with swim-throughs. In the north, the rocks are fully carpeted in soft corals and large, impressive sea fans where glassfish seek shelter behind, while the east area is dotted with hard coral and sea whips.
Trevally
All this is home to many species of fish. Large schools of barracuda, trevally, batfish, and snappers attend you at mid-water, especially around the mooring lines. Look for the dwelling Napoleon wrasse slowly swimming by. The rarely seen oceanic triggerfish can be found here too. These dark-colored triggerfishes usually live far away from the coast. Frequent sea turtle encounters count up another highlight at Koh Tachai Pinnacle.
Southern Pinnacle
From the north side of the southern pinnacle, a sandy patch at 24 meters depth leads you to the northern pinnacle, roughly 50 meters away. The top of the northern pinnacle lies at a depth of 18 meters. This smaller pinnacle resembles its bigger southern twin.
Koh Tachai Pinnacle offers everything, from stunning landscapes to macro life and big fish encounters.
And as always keep your eyes open; if the manta rays or whale sharks are not at Richelieu, they might visit Koh Tachai instead!
All about the dive at Koh Tachai Reef
Divers regularly encounter leopard sharks in the outer sandy area. Staghorn coral, brain coral, fire coral, and pore coral cover the entire area and attract the general reef fish like pufferfish, lionfish, scorpionfish, and parrotfish. Moray eels, spending the majority of their time hiding in holes and crevices for their own predators, are awaiting the perfect ambush of any unsuspecting prey. Despite their snake-like appearance, moray eels (along with other eel species) are in fact fish and not reptiles.
At night-time, several different species of crab and shrimp come out for hunting and been hunted.
Spotfin Lionfish
Then it is also possible to see a rare solitary species of Lionfish here too. The spotfin lionfish is easily separated from other species by the eye-spots on the dorsal fin and its Fu-Manchu mustache. It eats only live food like shrimps, gobies, and blennies. Adult spotfin lionfish will even eat smaller members of their own species. It is a secretive fish that spends the daytime hours hanging upside down in deeper crevices and caves. A diver might occasionally catch a glimpse of one of these fish moving from one crevice to another during the day.
Night dives
However, it is most readily observed during night dives, at which time it comes out to hunt. It exhibits an unusual behavior when it feeds. It will snap its dorsal spines and shake its head from side-to-side as it approaches its prey. This behavior may serve to distract, or possibly attract the prey. It often stalks its quarry by slinking along the bottom or around reef structure like a cat and moves forward, either by “hopping” on its pelvic fins or by waving its caudal fin. When it is about one-half a body length away from its prey, it lunges forward with amazing speed to ingest it.
All in all, Koh Tachai Reef makes a fine and easy dive, whether through the day or night.
