The Boiler

The Boiler, off San Benedicto, is the manta dive against which all others are measured. The pinnacle rises like a factory chimney from deep water to just under the surface, and giant oceanic mantas - black morphs and chevrons with wingspans past 5 m - come to it deliberately, banking through divers' exhaust bubbles and returning pass after pass with an interest nobody has fully explained. Clarion angelfish rise to clean them mid-water. Bottlenose dolphins interrupt dives at will, hammerheads shade the deeper water, and from January to March humpback song vibrates through the rock. Divers orbit the tower, keep hands to themselves, and let the animals run the encounter.

その瞬間のために: Giant mantas at point-blank range, dolphin visits, whale song through the water in late winter

地形: Round volcanic pinnacle rising from deep water to within 5-6 m of the surface

流れ（カレント）: An open-ocean tower; conditions range from serene to washing-machine within a single day.

危険生物・リスク: Open-ocean surge and current around a tower with no lee; mind depth when the mantas descend.

保全: Revillagigedo National Park prohibits touching mantas; operators enforce a no-chasing etiquette that the animals visibly reward.

ナイトロックス: ここでは価値があります。エンリッチドエア（ナイトロックス）が無減圧潜水時間を有意に延ばせる範囲にあるスポットです（利用にはトレーニングが必要です）。