The problem with hypothermia is that you don’t realise you’ve got it until it’s too late. As the blood is quickly drawn to the vital organs to keep them alive, you first lose coordination, then consciousness, then you die.
That’s if you’re not dead already. The biggest risk of subjecting the body to frigid temperatures – such as open fresh water of five degrees Celsius, or less – is a heart attack. Either way, not many people would survive longer than three quarters of an hour.
Only this Saturday morning, off the very cold shore of Lough Dan in the Wicklow Mountains, 16 people will subject themselves to those exact conditions, wearing nothing more than standard swimming togs, a cap, and goggles: they’ll swim for a mile, and provided the water stays at five degrees Celsius, or less, and they survive within 45 minutes, they’ll be rewarded with the title of International Ice Mile Swimmer.