Courtesy of Farther, Colder, Rougher – adventures in marathon swimming, San Francisco, California.

Evan Morrison pondered about one proposed definition of a cold water marathon swim: swimming 10 km unassisted at a maximum water temperature of 10°C (50°F) among his Marathon Swimmers Federation colleagues.

The benchmark is a tough one, but one in which probably more swimmers than imagined have already achieved as part of their longer marathon swims – or will be attempted and achieved over the next generation of hardened open water swimmers.

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