Among the many horrific experiments conducted by the nazis on their prisoners during WWII, a whole set of them focused on hypothermia: hapless Russian POW were put into icy water baths until they collapsed, then attempts to reanimate them using more or less scientific means were made.
Unlike most of their other pseudo-scientific experiments, this one actually had some kind of vaguely reachable goal: improve the life expectancy of the average Luftwaffe pilot forced into a sudden scuba-diving trip in the English Channel. Quite a problem at the time, especially among German tourists returning home from a leisure flight over London.