Dive Site: Koh Tachai Pinnacle

About Koh Tachai Pinnacle

Koh Tachai Pinnacle, located north of Koh Bon within the Similan Islands National Park, is a submerged granite boulder formation that many consider among Thailand's finest dive sites, often compared favorably to Richelieu Rock. This site is characterized by its dramatic underwater landscape, formed by gigantic granite boulders, canyons, and overhangs, creating a stunning and diverse environment for marine life. The pinnacle rises from depths of over 40 meters, with its shallowest point around 10 to 12 meters, making it accessible for various dive profiles. The site comprises two distinct pinnacles: a larger southern pinnacle, known as 'The Dome,' which is the primary dive area, and a smaller northern pinnacle connected by a sand patch at 24 meters, offering pristine coral gardens and sea fans. Koh Tachai Pinnacle is a hotspot for large pelagic species, with nutrient-rich currents attracting immense schools of predatory fish like giant trevally, bluefin trevally, dogtooth tuna, and barracuda. Lucky divers, especially between January and May, might encounter manta rays and whale sharks drawn to these feeding grounds. The vibrant hard and soft corals, coupled with impressive sea fans, adorn the boulders and shallower sections, supporting a rich ecosystem of reef fish, moray eels, and various macro life. The currents at Koh Tachai are a defining feature, ranging from moderate to very strong and often unpredictable. These currents, while challenging, are precisely what make the site so biologically rich and dynamic. Divers typically descend using a mooring line to reach the more sheltered areas among the boulders, where they can observe the incredible marine activity. Visibility is generally excellent, often exceeding 20 meters, though it can vary with conditions. Diving Koh Tachai Pinnacle offers an exhilarating experience for advanced divers, promising encounters with schooling fish and large marine creatures in a dramatic underwater setting. The site is a key attra

Dive site facts: Koh Tachai Pinnacle

Depth

10–40+ m

Typical dive

12–30 m

Current

Moderate to very strong

Visibility

10–40+ m

Water temperature

27–31 °C

Entry

Moorings / negative entry recommended

Level

Intermediate / Advanced

Dive type

Pinnacle, pelagic, drift

Night dive

Not recommended

Region / port

Similan Islands, Andaman Sea

Coordinates

9.075, 97.815

Conditions & Currents

Koh Tachai Pinnacle is renowned for its moderate to very strong and often unpredictable currents, flowing primarily northeast to southwest. These currents are a key factor attracting the abundant pelagic life but necessitate careful dive planning. Divers typically initiate their descent on a mooring line, allowing for a controlled entry into the often turbulent water column. Once divers reach the main pinnacle, the massive granite boulders offer considerable protection from the strong surge, creating calmer pockets to observe marine activity. Visibility is generally excellent, ranging from 10 to 40 meters, but strong currents can sometimes stir up sediment or introduce thermoclines, which may temporarily reduce clarity in localized areas. Due to these strong currents and the site's exposure, night diving is generally not recommended or offered by most liveaboards for safety reasons. Expe

Marine life & sighting chances

Manta ray

January-May · occasional

Whale shark

January-May · occasional

Giant Trevally

common

Bluefin Trevally

common

Dogtooth Tuna

common

Rainbow Runner

common

Chevron Barracuda

common

Batfish

common

Brown-marbled Grouper

common

Snapper

common

Moray Eel

common

Scorpionfish

occasional

Leopard Shark

occasional

Lionfish

common

Dive profile & how the dive runs

Diving at Koh Tachai Pinnacle typically begins with a descent along one of the two mooring lines, crucial for navigating the often strong surface currents. Divers quickly drop to the main southern pinnacle, 'The Dome,' which starts around 10-12 meters. The dive then proceeds around the colossal granite boulders, which form canyons and overhangs, offering some shelter from the current. You'll explore depths down to 30 meters or more, observing the vibrant hard and soft corals and the schooling pelagic fish. A common route involves traversing the southern pinnacle, potentially crossing a sandy patch at 24 meters to reach the smaller northern pinnacle, approximately 50 meters away. This northern pinnacle offers a slightly shallower top at 18 meters, adorned with large sea fans. The dive typically concludes with a safety stop in a more sheltered area of the main pinnacle, ensuring a safe ascent after exploring the rich topography and abundant marine life.

Underwater photography

Koh Tachai Pinnacle is a prime location for wide-angle photography, capturing the dramatic boulder formations, extensive soft coral gardens, and the sheer volume of schooling fish. A fisheye or wide-angle lens is ideal for showcasing the panoramic underwater scenery and vast schools of trevally and barracuda. Patience is key when strong currents are present, as pelagic action can be fast-paced. Be prepared for opportunities to photograph manta rays or whale sharks, making a good strobe setup essential for vibrant colors at depth. For macro enthusiasts, there are still subjects like scorpionfish, moray eels, and nudibranchs among the crevices and coral, although the site's primary draw is its larger inhabitants and expansive landscapes. Good buoyancy control is paramount, especially when navigating currents, to avoid damaging the delicate corals and to maintain stable shots.

Combine with nearby dive sites

• Richelieu Rock

  Often combined in liveaboard itineraries, known for whale sharks and diverse marine life.

• Koh Bon

  Popular for manta ray sightings and diverse reef life.

• Elephant Head Rock

  Another Similan pinnacle with intricate swim-throughs and strong currents.

• Hin Muang

  Famous for its purple corals and potential for pelagic encounters.

Getting there & logistics

Access to Koh Tachai Pinnacle is primarily via liveaboard trips originating from Khao Lak or Phuket, with journeys typically lasting 2 to 6 nights. Day trips are also available from Khao Lak, often involving fast catamarans or speedboats, but liveaboards offer the most comprehensive diving experience, including multiple dives at this and surrounding sites. The Similan Islands National Marine Park, which includes Koh Tachai, charges a national park fee, usually included in tour packages. The park is closed from May 16th to October 14th annually. Most itineraries combine Koh Tachai with other Similan and Surin Islands dive sites like Koh Bon and Richelieu Rock, offering a diverse array of dive experiences.

Safety & environment

Diving at Koh Tachai Pinnacle requires adherence to strict safety protocols due to the unpredictable and strong currents. Divers should possess advanced open water certification and experience in current diving. Always follow your dive guide's briefing regarding entry points, current mitigation techniques, and emergency procedures. Essential safety gear includes a surface marker buoy (SMB), whistle, and a dive computer. Dive insurance with comprehensive coverage for recompression chamber treatment and emergency evacuation is highly recommended. The nearest recompression chamber is in Phuket, requiring potentially lengthy evacuation times. Given the site's remote nature, avoiding solo diving and always having a well-briefed buddy are crucial. Maintain good buoyancy, monitor air consumption closely, and be prepared to make negative entries if conditions demand.

Who it suits — and who it doesn't

FAQ

Koh Tachai Pinnacle FAQ

Liveaboards diving Koh Tachai Pinnacle

These liveaboards may visit Koh Tachai Pinnacle on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Mandarin Queen 9

Thailand

26 guests37.5 m

Manta Queen 8

Thailand

24 guests

$127/day

The Junk

Thailand

18 guests33 m

$163/day

Deep Andaman Queen

Thailand

23 guests30.5 m

$194/day

Explorer

Thailand

16 guests25 m

$150/day

Andaman

Thailand

20 guests26 m

$108/day

Stingray

Thailand

8 guests24 m

$245/day

Seatopia

Thailand

24 guests24 m