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Koh Tachai Liveaboard Diving

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Liveaboard Diving in Koh Tachai

What To Expect On A Koh Tachai Liveaboard

Liveaboards to Koh Tachai usually visit this area on a Similan Islands itinerary on their way to Richelieu Rock. It's only 12 square kilometers in size and is located northwest of Similan Islands National Park; it lies between the Similan and Surin Islands. An idyllic location in the Andaman Sea, this small uninhabited island comprises a lush rainforest, stunning white sandy beaches, and crystal clear waters. Relatively untouched Koh Tachai is still unspoiled and worth the visit on your liveaboard dive cruise. Below the surface, some other visitors include whale sharks, manta rays, leopard sharks, and Napoleon wrasse, to name just a few. The waters around the island are quite shallow towards the shore, then drop off suddenly to depths of 70 meters. These drop-offs act as a barrier and protect the island, and its rich waters offer excellent snorkeling.

What You Can See

There are two great dive sites at Koh Tachai: the plateau to the south and the eastern reef. The sheltered, shallower waters off the eastern coast make for good night dives. Most liveaboards will moor here for the night.

Koh Tachai plateau, about 1km southeast of the island, is so named because it is ringed by a ridge-like coral plateau crowned with hard corals, gorgonian sea fans line the scattered boulders, sloping from 12 - 35 m to the sandy bottom where leopard and nurse sharks lie peacefully undisturbed. Groups of snapper lurking on the top ledges, octopus hiding amongst the corals, under which red-banded cleaner shrimp work tirelessly. It is best to pay close attention to the divemaster's brief as this site can sometimes be challenging, although the swim-throughs provide shelter from the strong currents. There is a decent line from a buoy on the south side, helping the diver to descend in sometimes strong surface currents. This site is for the more experienced diver. Towards the end of the dive, you may see coral-eating Hawksbill turtles, groups of batfish, or even the banded sea snake lurking near the mooring line upon your ascent. Keep an eye out for the odd Napoleon wrasse patrolling the area.

Koh Tachai pinnacle is usually done as a drift dive, and here, the currents bring high levels of plankton during February - April, and in turn, the larger pelagics feeding on them, such as the Manta Ray and Whale Shark. The strong currents enable the barracudas, trevallies, and sharks to hunt easily for smaller prey. Early morning dives can wake you up from your slumber quite quickly as it can sometimes be a feeding frenzy, and you may not know where to look as there are so many fish. Visibility varies on the month and the amount of plankton in the water, between 10-30m. If the larger pelagics are not shown, then be on the lookout for the macro life. Small frogfish and nudibranchs are known to grace these waters.

An impressive underwater topography mixed with diverse marine life makes Koh Tachai a must for Surin or Similan cruises.

Getting There

The best way to get to Koh Tachai is on a Thailand liveaboard trip to the Similan or Surin Islands, which will depart from either Phuket or Khao Lak. Further from Phuket than from Khao Lak (200 km north of Phuket and 80 km northwest of Khao Lak), it is worth checking what port you prefer to depart from. Khao Lak is about 100km north of Phuket and can be reached overland. Please check your itinerary before purchasing flight tickets. There are international flights into Phuket and domestic flights from Bangkok to Phuket. Reachable from Khao Lak in one hour, you may find other day boats in the area.


At Koh Tachai, scuba divers will encounter whale sharks, manta rays, leopard shark and nurse sharks for an exciting underwater adventure.


Koh Tachai Diving Reviews

  • Rating 9.1 out of 10
  • 9.1 Superb
  • Rating 9.6 out of 10
  • 9.6 Exceptional
  • Michael B
  • Flag of United StatesUnited States

2nd best location. The only sharks were black tips on the last night dive.

Diving Koh Tachai in December on the Bavaria
  • Rating 9.6 out of 10
  • 9.6 Exceptional
  • Steven W
  • Flag of United StatesUnited States

Wonderful location, beautiful scenery both above and below the water.

Diving Koh Tachai in December on the Explorer
  • Rating 10.0 out of 10
  • 10.0 Exceptional
  • Can A
  • Flag of United StatesUnited States

Loved the biodiversity, but also the crazy navigation around a complex environment.

Diving Koh Tachai in December on the Manta Queen 1
  • Rating 10.0 out of 10
  • 10.0 Exceptional
  • Olivia L
  • Flag of United StatesUnited States

So beautiful and unique! Incredible marine life and underwater features.

Diving Koh Tachai in October on the Deep Andaman Queen


What to know about diving in Koh Tachai

Is Koh Tachai open in 2026?

As of 2026, Koh Tachai remains officially closed to visitors, though Thai park authorities have announced plans to reopen it under a strict visitor cap; no confirmed reopening date has been set as of this writing, so check current status before building it into an itinerary.

Why did Koh Tachai close?

The island was shut down due to "over-tourism" — a sharp, short-term spike in visitor numbers caused significant damage to its coral reefs and beach ecosystem, prompting Thailand's national park department to close it for recovery.

When did Koh Tachai close?

Koh Tachai was closed indefinitely starting October 15, 2016, by the Department of National Parks, Wildlife and Plant Conservation.

Is Koh Tachai reopening?

Thai authorities announced reopening plans discussed in late 2025 and 2026, proposing a cap of around 100 visitors per day and a 6-hour visit limit, but as of 2026, no firm reopening date has been confirmed — the plan remains under discussion.

What is Koh Tachai known as?

It's nicknamed the "Pearl of the Andaman" for its powder-white beach and clear turquoise water, a reputation that contributed to overcrowding and ultimately led to its closure.

Can you dive at Koh Tachai as of 2026?

The surrounding waters, including Koh Tachai Pinnacle, have generally remained accessible to dive boats even while the island itself stayed closed to landings, but rules can shift — divers should confirm current access with their operator before counting on it.

What marine life is Koh Tachai famous for?

Koh Tachai Pinnacle is known for large schools of fusiliers and barracuda, manta rays, and occasional whale sharks, similar to nearby Koh Bon and Richelieu Rock.

How many visitors will be allowed at Koh Tachai when it reopens?

Proposed plans discussed in late 2025 called for capping visits at around 100 people per day with a maximum 6-hour stay, though these figures were still provisional as of 2026 pending a final reopening decision.

Where is Koh Tachai located?

Koh Tachai sits in the Andaman Sea between the Similan Islands and the Surin Islands, off the coast of Phang Nga province, making it a natural stop on itineraries connecting the two island groups.

Is Koh Tachai part of the Similan Islands National Park?

It's administered as part of the same national park system covering the Similan and Surin Islands, which is why its closure and any future reopening follow the same park department rules.

How long was Koh Tachai closed?

As of 2026, Koh Tachai has been closed for roughly nine years since its October 2016 shutdown, one of the longest island closures in Thailand's national park system.

What caused the environmental damage at Koh Tachai?

A rapid surge in day-trip visitor numbers led to beach erosion, coral damage from anchors and foot traffic, and litter overwhelming the small island's capacity to recover between visits.

Will there be a time limit for visiting Koh Tachai?

Yes, under the reopening plan discussed by Thai authorities, visits would be capped at 6 hours per day, along with the 100-person daily limit, though final rules were not yet locked in as of 2026.

Is Koh Tachai reachable by liveaboard?

Yes — Koh Tachai sits directly on the route between the Similan and Surin Islands, so liveaboards already pass close by and often dive Koh Tachai Pinnacle even while the island itself has stayed closed to landings.

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