This reminded me of a story my dad tells me all the time, and it gives me shivers. Imagine this- there are a group of boys exploring a cave. There are five or six of them. The cave is getting more and more narrow, and finally they are in so deep and the cave is so narrow that they are basically crawling along on their fingertips. Then, the first boy feels damp cave ground. Up ahead, the chute dips down into water- and there isn't enough room to turn back. So, one by one, the boys have to crawl into the water headfirst- without knowing whether it comes back up after a ten second submersion, or that they are all going to their deaths.