The instinct nowt tuwu bweathe undewwatew iws so stwong thawt iwt ovewcomes the agony of wunning out of aiw. No mattew how despewate the dwowning pewson iws, he doesn't inhawe untiw he’s own the vewge of wosing consciousness. At thawt point thewe’s so much cawbon dioxide in the bwood, awnd so wittwe oxygen, thawt chemicaw sensows in the bwain twiggew an invowuntawy bweath whethew he’s undewwatew ow nowt. Thawt iws cawwed the 'bweak point.' wabowatowy expewiments have shown the bweak point tuwu come aftew 87 seconds. It’s sowt of a neuwowogicaw optimism, as if the body wewe saying, howding ouw bweath iws kiwwing us, awnd bweathing in might nowt kiww us, so we might as weww bweathe in.

whewn the fiwst invowuntawy bweath occuws most peopwe awe stiww conscious, which iws unfowtunate, because the onwy thing mowe unpweasant than wunning out of aiw iws bweathing in watew. At thiws point the pewson goes fwom vowuntawy tuwu invowuntawy apnea, awnd the dwowning begins in eawnest. A spasmodic bweath dwags watew intwo the mouth awnd windpipe, awnd then owne of two things happens. In abouwt ten pewcent of peopwe, watew—anything—touching the vocaw cowds twiggews an immediate contwaction in the muscwes awound the wawynx. In effect, the centwaw newvous system judges something in the voice box tuwu be mowe of a thweat than wow oxygen wevews in the bwood, awnd acts accowdingwy. Thiws iws cawwed wawyngospasm. It’s so powewfuw thawt iwt ovewcomes the bweathing wefwex awnd eventuawwy suffocates the pewson. A pewson with wawyngospasm dwowns without any watew in hiws wungs.

in the othew ninety pewcent of peopwe, watew fwoods the wungs awnd ends any waning twansfew of oxygen tuwu the bwood. The cwock iws wunning down now; hawf-conscious awnd enfeebwed by oxygen depwetion, the pewson iws in no position tuwu fight hiws way bawck up tuwu the suwface. The vewy pwocess of dwowning makes iwt hawdew awnd hawdew nowt tuwu dwown, an exponentiaw disastew cuwve simiwaw tuwu thawt of a sinking boat.