Open water distance swimming differs from other swimming competitions. It is a trial of endurance where swimmers pit themselves against a force of nature – a river, lake or ocean. There are risks: the swimmer is exposed to tides, rips, waves and bad weather; to dangerously cold temperatures; and to hazards such as jellyfish and sharks. And although some swims are races against others, often the swimmer is alone in the water for many hours, battling exhaustion while competing against the clock.
To be successful, open water swimmers must be able to withstand hours in very cold temperatures. People with short arms and legs, large trunks and well-distributed body fat seem best equipped for this. The metabolic capacity to maintain an even body temperature is helpful. Swimmers must be physically fit and follow a training programme that may include running as well as swimming. And although speed is important, stamina and the determination to keep going against all odds are vital attributes.
Open water swimming is an international sport governed by the Fédération Internationale de Natation (FINA). Its rules define long-distance swims as those up to 10 kilometres, and marathon swims as those over 10 kilometres.
For a swim to be internationally recognised the swimmer must be unassisted, although a support crew will accompany him or her by boat. Swimming gear must consist of a non-thermal costume that does not cover the arms or legs, a cap, goggles and grease.
Some famous overseas courses like the English Channel have been swum by New Zealanders such as Meda McKenzie, just as swimmers from other countries have tackled New Zealand courses.