Once on the Spree in the Gulf of Mexico we had been diving 5-6 times a day and I think the dry nitrox got to my sinuses. I had trouble clearing going down and at about 60’ my sinuses dumped a load of flem and I couldn’t breathe but I was finally able to move it and surface.
Dive related but not me underwater, I had just read a story about a commercial diver buried in mud under a boat in San Francisco Bay and can imagine being trapped and unable to move for the better part of a day thinking about when was the last time he had serviced his compressor that was feeding him air. For weeks after that I couldn’t sleep in a dark room!