Heimaey is the largest of the Westman Islands, an archipelago south of Iceland mostly inhabited by puffins. On Stórhöfði peninsula, at the southernmost point of Heimaey is an outcrop that juts into the Atlantic Ocean. The local weather station here claims to be one of the windiest places in Europe.

It was here, in the early hours of March 12 1984, that 23-year-old Guðlaugur Friðþórsson stumbled towards salvation. His bare feet were bleeding from deep cuts caused by the volcanic rock hidden beneath the snow, his clothes soaked in seawater and frozen to his body. He should have already died several times over, but something deep inside Friðþórsson propelled him forwards.

The night was clear and cold. The air temperature was -2C (28F) but with strong winds it would have felt much colder. Despite the freezing temperatures, he paused at a bathtub filled with water left out for sheep for a brief respite. Punching through the centimetre-thick ice he began to gulp down water from the trough.

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It is perhaps strange that a drink of ice cold water was a primary concern at a time like that. But dehydration is a surprising concern in cold environments as the air in sub-zero temperatures is essentially freeze-dried. With no moisture in the air, when he breathed out, he was losing vital fluid from his lungs. It is why you can see your breath hanging in the air on a cold night.

But the cold also appears to blunt our sensation of thirst, meaning many people do not take in enough water. If you are working hard to stay warm, and breathing heavily as a result, it can quickly lead to dehydration.