Koh Tachai Pinnacle

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.

その瞬間のために: Trevally tornadoes in ripping flow, manta and whale-shark transits, big-current craft

地形: Submerged granite dome with boulder terraces

流れ（カレント）: Among Thailand's strongest-current sites; some slots are simply undiveable and crews wait for the tide.

エントリー: Descents run down a fixed line to the dome; in strong flow, crews stage negative entries and shorten the plan.

危険生物・リスク: Severe current, down-eddies off the dome's flanks, and blue-water ascents; SMB and line discipline are mandatory.

保全: Koh Tachai's land closure is a park recovery measure; the pinnacle stays open under standard park rules.

ナイトロックス: ここでは効果的です——このエリアのプロファイルは、ナイトロックスが無減圧潜水時間を有意に延ばせる水深帯にあります（適切なトレーニングを受けていることが前提です）。