I fell in one when I was 14, back in the winter of '97. Some old skier dude saw me fall in and dug/pulled me out. I fell in arse first and was wedged in folded up with my head jammed between my legs. There was no way for me to get myself out - I couldn't move an inch and could hardly breath to yell for help because my diaphragm was totally compressed on account of the way I was folded over. That stranger likely saved my life.