Tips (and a point of comparison) from an Arctic diver.
According to Christoph, “The water can chill down here to about -1.8 degrees Celsius.” As I checked Google to find that this converts to about 28 degrees Fahrenheit, he chimes in, “I know, that doesn’t sound so bad.” (I assure him that yes, it does indeed sound very bad.) “Water transports heat 25 times faster than air,” he says, “when you multiply [that water temperature] by 25, then you get to somewhere between -40 and -50 degrees in equivalent air temperature.”
While diving in the Arctic is cold, your body ignores that fact pretty soon. “My experience is that it’s not so bad. You go into the water and you get really cold and you get all these needles and pins, and it hurts for a couple seconds, but then it’s numb and then it’s fine!” For commercial dives, Christoph can be in the water for up to three hours at a time. “If you were just sport diving, bobbing in the water and sightseeing, you would last 20 minutes, half an hour, and then you would start getting cold and thinking of coming up and getting back out of the water. Whereas when you are working under the water, it is very different. You are active. You are moving, lifting heavy things—this keeps the blood circulating and makes you last much longer underwater.”