2 Big 2 Fail
Contributor
A reverse block wont kill you, but you should definitely be aware of the potential effects. I was on a boat with a diver who blew out an eardrum. They had a brief moment of sharp stabbing pain and experienced extreme vertigo and nausea when the cold water flooded his ear.
We didn't know what was wrong, but we saw him turning kind of topsy turvy as his equilibrium was compromised. We got him to the anchor line and after a few minutes he regained his bearings. He was able to surface without further incident, although he did have some rather nasty discharge from that ear.
It's difficult to say what the outcome might have been if this had been a free water ascent, without an anchor line or several other people around to help him back to the anchor line.
You're right. It's not trivial. Vertigo is a wild and scary thing to someone who's never had it. I actually had it for a while many years ago. It took a good while to learn how to ignore it and switch to the other senses and have faith in things like the reality that the Earth isn't flopping around - or in the case of diving, that you're not really caught in a blender. It's funny how things that seemed so bad at the time turn out to maybe prepare you for something in the future. If I blew out an ear and had vertigo underwater now, I'd be able to relax, observe the spinning environment, and engineer myself to the surface. Nietzsche was sort of right.