The 350 acre Park, in the heart of central London, is one of the capital’s most famous and iconic landmarks and will host the triathlon and open water swimming events for men and women in 2012.

The 55 men and 55 women participating in the triathlon will swim one 1500 metres lap of the Serpentine, departing from a pontoon placed on the north side of the lake.

They will then cycle seven laps, or 40 kilometres, in and out of the Park before running four laps around the Park to complete the third discipline, the 10km run.

The cycle route, which must go outside the Park for an Olympic event, will exit at Hyde Park Corner before going down Constitution Hill, past Buckingham Palace and back into the Park.

"For the athletes it will be fantastic to be in the heart of the city," said Debbie Jevans, Director of Sport for London 2012. 

"For spectators it allows them to get close to the action."

It will be the first time triathlon has been held in the centre of the host city since it made its debut as an Olympic event in Sydney in 2000.

The cycle course differs from the one used in the recent International Triathlon Union (ITU) World Series where the entire event was contained within the Park.

"In Beijing it was sterile," said John Lunt, the London 2012 triathlon competition manager.

"There was no atmosphere. 

"London will be all about the spectator experience."

In the first three Olympics, 1896, 1900 and 1904 all the swimming events took place in open water before moving to the pool. 

The 10km marathon swim was first introduced in Beijing in 2008.

Like the triathlon, the open water swimming will be different In 2012 as it will comprise of six laps of the Serpentine, each of 1.67km, rather than four.

"In open water swimming every event is different from the one before," said Britain's Cassie Patten who won bronze in the 10km Marathon in Beijing (pictured). 

"We’ve got two years to get used to six laps."

Details were also released of the temporary, 15,000 seat Arena to be constructed at Horse Guards Parade for the beach volleyball.

Some spectators will enjoy views out towards Whitehall and beyond to the London Eye.

Work will begin on the structure in June 2012 and it will be removed in September.

The triathlon will take place over two days in August 2012 followed by two days of marathon swimming.

Details have yet to be released about the actual date of the triathlon although London Mayor, Boris Johnson said earlier in the year he wanted some road events moved to weekends in order that more Londoners, who would be working during the week, could enjoy events first hand.

Hundreds of thousands of spectators are expected to attend events such as the triathlon as they are non-ticketed and offer thousands of different vantage points for free.