By Denis Balibouse
GENEVA (Reuters) - It's twice as far as crossing the English Channel and known as the "Ultimate Trophy Swim".
Three amateur swimmers -- two in their late forties and one in his early sixties -- are the latest to have completed a 70-kilometre (43.5 miles) relay swim across Lake Geneva, one of Europe's largest lakes.
The British-based trio, who took it in turns to swim two-hour legs, completed the non-stop swim on Tuesday in 32 hours and seven minutes.
"At night it was very, very difficult. It was dark and, you have to swim with lights, lights on your head, lights on your backside and lights on the boats," said Dirk Gewert, a 62-year-old German research scientist who works in the pharmaceuticals industry in Britain.
"You don't see things very well and also the wind starts coming up and it was very choppy, so it was going up and down, and it was really hard.
"Then, when sun rises, it gets calmer, then it gets better ... but swimming for 10 hours overall is, is a lot. It hurts."
The relay began at the Chateau de Chillon, a medieval fortress at the eastern end of the lake, and finished in Geneva itself.
The record time the swim has been completed in stands at around 23 hours. Local regulations required that for the swim to go ahead, it needed two coast guards on standby, a fully equipped escort boat, two pilots and two official observers, including a fully trained lifeguard.
"I think the sport is more about the mental aspect than it is about the swimming," said Nicola Naunton, another member of the team. The 47-year-old, who works in the financial services industry, said she was a couch potato until three years ago.
"My shoulders are fine, they don't hurt at all, but my mind is quite tired and I think we all had to support each other."
Peter Whitehead, a 48-year-old bank worker in London, completed the team.
"Some people climb mountains, other people jump out of air planes and go sky diving, we just go swimming," he said. "Everyone has their element of madness."