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21 km away as the crow flies
Phuket · Thailand · Asia
Max. depth · 32 mKoh Doc Mai, Phuket: Wall Diving and Caves
Explore the vibrant limestone walls of Koh Doc Mai, rich in macro life, diverse corals, and intriguing caves.
What makes this site special
- Dramatic vertical limestone walls
- Abundant macro life including nudibranchs and ghost pipefish
- Presence of tiger tail seahorses and frogfish
- Large and small caves on the east wall
- Schools of snappers, trevallies, and fusiliers
- Leopard sharks and bamboo sharks at depth
- Exposed to strong currents, offering drift dives
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Koh Doc Mai about the site
Koh Doc Mai is a distinct limestone pinnacle emerging abruptly from the Andaman Sea, approximately 20 kilometres east of Phuket. Its primary feature is a dramatic vertical wall that plunges into the depths, forming a diverse underwater landscape. Unlike a traditional reef, exploration here focuses on these sheer faces, which are rich with marine growth and hidden life, with no land access to the island itself.
The dive unfolds along these extensive limestone formations, with the walls descending to a maximum depth of 32 metres. The eastern side of the island is particularly popular, distinguished by its complex topography, numerous fissures, and crevices throughout its entire depth range. This side also features both a larger, more accessible cave and a smaller, narrower one, demanding specific training for safe penetration due to its constricted nature.
Macro enthusiasts will find Koh Doc Mai particularly rewarding. The walls are a canvas for species like colorful nudibranchs, flatworms, and various shrimp, including the energetic dancing shrimp. Close observation of gorgonians and soft corals often reveals ornate ghost pipefish and elusive tiger tail seahorses, perfectly camouflaged within their surroundings. Patience is key to spotting these intricate, smaller inhabitants.
Beyond macro life, the site hosts a range of larger reef dwellers. Schools of yellowline snappers, trevallies, and fusiliers are frequently seen along the length of the wall. Keep an eye on the blue for large barracudas. Deeper along the sandy bottom, leopard sharks can occasionally be spotted resting, often accompanied by bamboo sharks found concealed within crevices or caves.
This dive site is dynamic, with currents ranging from moderate to strong. These currents frequently deliver nutrient-rich waters, contributing to the healthy marine ecosystem. While stronger currents can create an exhilarating drift dive experience, they demand good buoyancy control and situational awareness, especially when exploring wall sections or planning entry and exit points.
Visibility at Koh Doc Mai typically ranges from 5 to 20 metres, but it can fluctuate significantly with conditions. Despite variations, the site’s dense marine life makes it a consistent favorite. This versatility allows for rewarding dives throughout the year, including the rainy season, showcasing its vibrant ecosystem regardless of external conditions.
Diving Koh Doc Mai: the marine life you’ll meet
Nurse sharkGinglymostoma cirratumWhale sharkRhincodon typusBamboo sharkChiloscylliumOrnate ghost pipefishSolenostomus paradoxusFlatwormTurbellariaCleaner shrimpLysmataLeopard sharkTriakis semifasciataGhost pipefishSolenostomidaeBigeye trevallyCaranxShrimpCarideaFrogfishAntennariusButterflyfishChaetodon
See 10 more species
TunaThunnusFusilierCaesioSnapperLutjanusScorpionfishScorpaenidaeReef sharkCarcharhinusJackCarangidaeMoray eelMuraenidaeButterflyfishChaetodontidaePipefishSyngnathidaeYellowtail barracudaSphyraena flavicauda
Diving conditions
Koh Doc Mai is generally considered an advanced dive due to potentially strong currents and depths up to 32 metres. Experience with currents is advisable. While certified divers can explore sections of this site, those considering penetration into the smaller, narrower caves should hold a cavern or equivalent specialty certification. Visibility typically ranges from 5 to 20 metres.
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Frequently asked questions about Koh Doc Mai
When should you dive Koh Doc Mai?
You can dive Koh Doc Mai throughout the year, including the rainy season. Visibility typically ranges from 5 to 20 metres and may fluctuate with conditions. Its dense marine life remains present through these variations, so the site can offer rewarding exploration whenever you visit.
What experience level do you need for Koh Doc Mai?
Koh Doc Mai is generally considered an advanced dive because of potentially strong currents and depths up to 32 metres. You should have experience with currents. Certified divers can explore some sections, while entering the smaller, narrower caves requires cavern or equivalent specialty certification.
How deep is Koh Doc Mai?
Koh Doc Mai reaches a maximum depth of 32 metres, with dramatic limestone walls descending into the Andaman Sea. The eastern side contains fissures and crevices throughout its depth range, plus larger and smaller caves. The smaller cave is narrow and requires specific training for safe penetration.
What currents and marine life can you encounter at Koh Doc Mai?
Koh Doc Mai has moderate to strong currents that can create drift dives and require good buoyancy control and situational awareness. Along the walls, you may see nudibranchs, ghost pipefish, tiger tail seahorses, frogfish, snappers, trevallies, fusiliers, barracudas, leopard sharks, and bamboo sharks.
