Foster's company Nova International are expecting 2,200 competitors to take part in the Great North Swim, a one mile across across Lake Windermere in Cumbria and the first mass-participation swim of its kind ever staged in Britain.

Among those due to take part are the first three from the 10 kilometres open water swim at the Beijing Olympics, including the gold and silver medallists, Holland's Maarten van der Weijden and Britain's David Davies.

Keri-Anne Payne and Cassie Patten, the silver and bronze medallists in the women's open water event, will also take part, along with Joanne Jackson, who finished third in the 400 metres freestyle behind Rebecca Adlington in Beijing.

But to Foster the most important thing is the amount of ordinary people who are taking part in an event that joins an already impressive portfolio organised by Nova that includes the Great North Run, the half-marathon from Newcastle to South Shields founded in 1981 and which now has a record 52,000 entrants, and a range of other road running events across the country that are held over a variety of distances.

Foster, the 1976 Olympic 10,000m bronze medallist and now a member of the BBC TV commentary team, said: “The Olympics has always tried to produce a participation spin-off, but evidence does not show this is the case.

“In the build up to 2012, we have the opportunity to motivate people to get more active and take part in mass participation events.

“If we provide enough inspiring, challenging and exciting events in a range of activities, then people will respond with, ‘I can do that!’

“Lots of mass participation running events exist and, as this extends out into other sports such as swimming, cycling, walking and dance, the opportunities are even greater.

“Scientific evidence shows that in giving the stimulus of an event, it is the event itself and the commitment to it that changes people’s lifestyles and increases their activity levels.”

Davies said: “I really do think this event can become as big as the Great North Run.

"The amount of people that have entered for this first one shows it’s going to be really popular.

“The lake is just beautiful.

It’s my first time up here and the scenery is a beautiful backdrop for the race."

Others taking part include Mark Foster, who carried the flag for Britain during the Olympic Opening Ceremony in Beijing last month.

Foster, whose specialist distance in the pool was 50m, said: “The response from the public has been phenomenal and to have 2,200 swimmers of all abilities taking to the water is a real achievement for the sport.

Van der Weijden is the ideal figurehead for an event such as this because he has such an inspiring story having survived leukaemia to become an Olympic gold medallist.

He said: “I am just lucky that the chemotherapy saved me.

"That’s how simple it is.

"I even think it’s dangerous because it implies that if you are not a positive thinker all the time you lose.

“The doctors - and not just the power of positive thinking and my love of sport - have saved me.

“It taught me to think step by step and be patient.

"When you are in so much pain lying in a hospital bed you aren’t thinking about the next month, but the next hour.

“This is the same strategy I use in the pack when we are racing and waiting my chance.

“Seven-and-a-half years ago I was fighting leukaemia.

"Because of the stem cell transplant I received I had the luck to recover.

"So everyone who has donated money to cancer research in the past, I am extremely grateful to them.

“Maybe I wouldn’t be here otherwise.”