I did something like this unintentionally one year ... as kids we were running down a frozen creek in the area never suspecting a thing when I found some thin ice and needless to say ... disappeared from sight.
I wasn't in the water long enough to experience the "polar bear" effect, my only thoughts were getting out of that water so that the 50 pounds of winter clothing my mother insisted I wear, wouldn't drag me any farther under than I had already gone ...
Unexpected as it was, it wasn't any fun ... now if I was expecting or something I had intention of doing it might be a different story, I dunno ... haven't had that luxury yet.
Mebbe one day ... who knows.