Koh Tachai Pinnacle
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
South of Koh Tachai island, a granite dome crests around 12 m and takes the full force of the Andaman's tidal exchange, which is precisely why everything gathers there. Trevally spiral in dense chimneys, barracuda hold formation up-current, batfish wander the terraces, and both mantas and whale sharks transit often enough to keep every diver glancing at the blue. The diving is work: pull down the line, tuck behind granite, move in the lulls. The island's famous beach has been closed to tourism since 2016 for recovery, but this offshore pinnacle remains on liveaboard schedules, conditions permitting.
The moment you come for: Trevally tornadoes in ripping flow, manta and whale-shark transits, big-current craft
Topography: Submerged granite dome with boulder terraces
Current: Among Thailand's strongest-current sites; some slots are simply undiveable and crews wait for the tide.
Entry: Descents run down a fixed line to the dome; in strong flow, crews stage negative entries and shorten the plan.
Know before you splash
Hazards: Severe current, down-eddies off the dome's flanks, and blue-water ascents; SMB and line discipline are mandatory.
Conservation: Koh Tachai's land closure is a park recovery measure; the pinnacle stays open under standard park rules.
Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).
Who you'll meet
Giant Trevally
Great Barracuda
Pinnate Batfish
Reef Manta Ray
Whale Shark
For photographers
Wide angle: ★★★★★ · Macro: ★☆☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting