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Discover Koh Tachai

One of the smaller islands of the Similans archipelago...but...

One of the smaller islands of the Similans archipelago...but...
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Koh Tachai Island is located at the northern most tip of the Similan National Park. It is one of the latest additions to the National park area together with the island of Koh Bon.
The island measures 12 square kilometers...​

​On Koh Tachai you will find beautiful white beaches and azure crystal clear waters all around it...
​This extravagant marine life lead to the nomination of the National Geographic Society as one of the top 10 diving destinations in the world.


The only beach on Koh Tachai is about 800 meters long and faces east like on most of the Similan Islands. The rainforest reaches out and gives shade if the sun is getting to hot to endure. When you walk all the way up north you will be able to a small jungle trail that takes you to the Western side of the Island. Within 10 minutes you are in a totally different world full of rocks and have a beautiful view over the Island and the Andaman Sea.

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.

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 Rock, they might be at Koh Tachai instead!

​Dive Koh Tachai...
Ko Tachai dive site, also known as Twin Peaks is, along with Ko Bon, one of the most famous spots of the Surin Island National Park.
Tachai Pinnacle is the most famous dive spots around – it became a must-stop place on the journey of scuba diving live-aboard boats heading to Richelieu Rock from the Similan Islands (Koh Tachai is situated right in the middle of these two world-famous dive spots).

Marine life on the pinnacle is exceptional. Divers come here because of the regular manta ray sightings. Whale sharks are also seen here. Leopard sharks are common as are barracuda, trevally and tuna. Hawksbill turtles can be seen and Tiera Batfish are often hanging out near the mooring line.​
The place is also full of fan corals and majestic sea sponges​!
Koh Tachai pinnacle is a huge granite plateau covered of soft coral, sea fans, anemones, the strong current bring food from the depth and attract big school of fish...

Due to the exposed location of Koh Tachai Pinnacle the current during full and new moons can be quite strong.  If this is the case our expert guides will instruct you on how to use the mooring line to help you descend correctly and enjoy this wonderful dive site. Keeping close to the rocks and following your guides example will keep you out of the worst of the current and ensure you use the least amount of energy and air.
​

Sea turtle
Sea turtle
Koh Tachai
Koh Tachai
Koh Tachai from the sky
Koh Tachai from the sky
Barracudas school
In the shade of a Manta ray
In the shade of a Manta ray...
Giant Sea Fan in Thailand
Giant Sea Fans
Whale shark feeding
Whale shark feeding
FROM BANGKOK TO SIMILAN
​
The fastest way to reach Koh Tachai is to fly to Ranong and join a liveaboard diving cruise from there.
The usual North Andaman cruise usual visit Thailand's best dive sites:  from North to South Richelieu Rock in Surin National Park as well as Koh Bon and Koh Tachai in Similan National Park.
See our schedules

The Smiling Seahorse

Our dive cruises

170 Ruangrat Rd, Tambon khao nivet, Mueang Ranong District, Ranong 85000​
Phone: +66860110614​
​Mail: [email protected]

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  • When & Where
    • Schedule and Prices
    • Destinations >
      • North Andaman Thailand >
        • Similan Islands
        • Surin Islands >
          • Richelieu Rock
        • The essential Underwater photo Guide to diving Thailand
      • South Andaman Thailand >
        • Phuket & Koh Phi Phi National Parks
        • Koh Lanta National Park
        • Koh Lipe and Tarutao National Park
      • Mergui Archipelago >
        • Liveaboard diving holiday in Myanmar
        • Burma's best dive sites
        • The Ultimate Underwater photo Guide to diving Burma
  • ABOUT
    • Our Boat >
      • DELICIOUS FOOD
    • Diving in Thailand in 2024-2025
    • Diving in Myanmar/Burma in 2024-2025
    • Blackwater diving in Thailand and Myannmar
    • Marine life in Thailand's Andaman Sea
    • Marine life in Mergui Archipelago
    • Dive Courses >
      • Learn to Dive
      • Continue diving education
      • Rescue diver
      • Professional Dive Courses
      • Hone your dive skills with a specialty course
      • Photo coaching in Thailand on the Smiling Seahorse
    • Guest Book
    • FAQ
  • Plan your trip
    • Our hotels recommendations
    • Khao Sok National Park
    • Taxi services >
      • Taxi services to and from Ranong
      • Taxi services to and from Phuket
      • Taxi services to Tap Lamu and Khao Lak
    • 10 things to do around Ranong
  • PROMO
    • HOT DEALS
    • Special Expeditions >
      • 8D Special Marine Bio with Piers Baillie - 10 Nov 2025
      • 8D Whale shark expedition - 20 March 2026 - North and South
  • gallery
    • Photos
    • Videos
  • CONTACT
  • BLOG
    • Most popular posts