Aside from anything else, very cold water reduces the use of oxygen by your body and brain, and makes it possible to survive much longer than otherwise. I think

Aside from anything else, very cold water reduces the use of oxygen by your body and brain, and makes it possible to survive much longer than otherwise. I think there was a story in Gawande’s Checklist Manifesto about this property being used in an operating theatre to rescue a girl from a car accident in a Swiss lake.