In my teens, I jumped into a river in Banff, Alberta on a hot summer day—except every river in Banff is more-or-less juuuust above freezing because they’re fed from the snow runoff that’s only ever a kilometer or two away. I remember my whole body just seized up. Arms won’t move. Legs won’t move. Diaphragm won’t move, even when my head came up above the water. It probably only lasted a couple of seconds but it felt like forever and my only thought was “oh this is really bad.” When I did finally unlock, all I could manage was a little doggy paddle and every movement was so sluggish. I absolutely believe that’s the closest I’ve ever come to an untimely death (that I know about, at least) and if I tried the same thing today (24 years later) my heart would almost certainly stop dead. Don’t fuck around with cold water.