There's an oft quoted statistic that says a 50 year old man has only a 50% chance of surviving a 50 yard swim in 50 degree water.

Not sure where it comes from, but swimming in really cold water is unbelievably painful - and yes, I do one or two polar bear swims in the Atlantic each winter, so I know what I'm talking about! (This year wans't so bad. But some years, oh boy!) I've gone out in 36 degree water in a drysuit with insulating garments underneath, and that was no picnic to my hands, toes, and face!

I wouldn't be so cavelier about swimming to shore in cold water. . .