[ergothus]

My wife and I were doing a dive under very controlled circumstances. My wife tried to swim through a circular opening wider than your outspread arms. She couldn't. Fighting panic (rule 2: dont panic!) She kept trying, growing ever more aware of being both underwater and underground.

Then our dive master reached out and pushed her down a foot, and suddenly her tank could clear the top. From her perspective she kept swimming lower, but that was counteracted by buoyancy and she couldn't tell, with every failed attempt reducing her mental capacity to figure it out.

Fight or flight is not the reflex we need in diving, but it is the reflex we have.