I get so tired of the kind of hyperbole that opens this article. If an untrained person deliberately dives into 28F water mostly they get cold and quickly get out. How do I know this? Am I a physiologist? No. Am I survival expert? No. I took a trip to Antarctica and the tour operator let passengers dive into the water, swim to a nearby platform and get out. The group of braves souls was about a dozen in number and aged from mid-teens to mid-50's. I even have pictures.

Yes, if you unexpectedly fall into freezing water you can involuntarily inhale and drown. Diving in, swimming a few strokes and climbing out is nowhere near invariably fatal.

All the intrepid divers I saw survived unscathed.