British-based trio complete ultimate trophy swim across Lake Geneva

Swimmer Nicola Naunton looks on before swimming her leg of a 70 km relay swim across Lake Leman from Montreux to Geneva, in Evian-les-Bains, France, near Switzerland August 21, 2017. REUTERS/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.

Peter Whitehead swims at sunset during a 70 km relay across Lake Leman from Montreux to Geneva, near Evian-les-Bains, France, near Switzerland August 21, 2017. REUTERS/Denis Balibouse

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.

Swimmer Dirk Gewert reacts next to his wife, Connie, after struggling during a 70 km relay across Lake Leman from Montreux to Geneva, near Evian-les-Bains, France, near Switzerland August 21, 2017. Picture taken August 21, 2017. REUTERS/Denis Balibouse

"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.

Swimmer Dirk Gewert jumps into the water to swim his leg of the 70 km relay swim across Lake Leman from Montreux to Geneva, near Montreux, Switzerland August 21, 2017. Picture taken August 21, 2017. REUTERS/Denis Balibouse

"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.

Swimmer Nicola Naunton checks on teammate Peter Whitehead after completing her leg during their 70 km relay swim across Lake Leman from Montreux to Geneva, near Evian-les-Bains, France, near Switzerland August 21, 2017. Picture taken August 21, 2017. REUTERS/Denis Balibouse

"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."

(Additional reporting by Cecile Mantovani; Writing by Brian Homewood; Editing by Susan Fenton)

Swimmer Peter Whitehead recovers from his night shift during a 70 km relay swim across Lake Leman from Montreux to Geneva, near Yvoire, France, near Switzerland August 22, 2017. Picture taken August 22, 2017. REUTERS/Denis Balibouse

Swimmers Dirk Gewert (R), Nicola Naunton (L), and Peter Whitehead celebrate after swimming a 70 km relay swim across Lake Leman from Montreux to Geneva, at Bains des Paquis in Geneva, Switzerland August 22, 2017. Picture taken August 22, 2017. REUTERS/Denis Balibouse

Swimmer Peter Whitehead gestures to family and friends before his attempt to swim his leg of the 70 km relay swim across Lake Leman from Montreux to Geneva, in Veytaux, Switzerland August 21, 2017. Picture taken August 21, 2017. REUTERS/Denis Balibouse

Swimmers Dirk Gewert, Nicola Naunton, and Peter Whitehead celebrate completing a 70 km relay swim across Lake Leman from Montreux to Geneva, at Bains des Paquis in Geneva, Switzerland August 22, 2017. Picture taken August 22, 2017. REUTERS/Denis Balibouse

Peter Whitehead swims his leg of the 70 km relay across Lake Leman from Montreux to Geneva, near Villeneuve, Switzerland August 21, 2017. Picture taken August 21, 2017. REUTERS/Denis Balibouse

Skipper Caroline Fanouillaire shows swimmer Nicola Naunton the progress Naunton and her teammates made during their 70 km relay swim across Lake Leman from Montreux to Geneva, near Yvoire, France, near Switzerland August 22, 2017. Picture taken August 22, 2017. REUTERS/Denis Balibouse

Swimmers Peter Whitehead and Dirk Gewert use their mobile phones as teammate Nicola Naunton swims her leg of a 70 km relay swim across Lake Leman from Montreux to Geneva, near Yvoire, France, near Switzerland August 22, 2017. Picture taken August 22, 2017. REUTERS/Denis Balibouse