We had a guy BO during UWR pretty badly (was out on the bottom for :30 sec+ before he was noticed - freak situation) and he had his snorkel in his mouth as is normal in the sport.
When he was surfaced, he was clamped down so hard on the mouthpiece that we couldn't pry / pull it out....
Can anyone explain to me why the jaw would clamp down during a BO event? Is this something that always happens, sometimes happens; what's going on there?
What about when there is no snorkel in the mouth? Is it still clenched shut then? If so, at what point in the recovery does it relax and open up again?
Is this jaw clenching during BO an understood phenomena?