The Olympic Games returned to its roots on Wednesday when 25 women jumped into the waters of the rowing lake outside Beijing and stayed there for the next two hours.

The event was the 10km swimming marathon, an event new to the games but a self-conscious homage to the first modern Olympics 112 years ago, when all the swimming events took place in Piraeus Harbour.

The 1896 Olympics took place in April, an unusually cold one for Greece. The swimmers had to battle with frigid water and, for the 1500m race, 12ft waves. “My will to live completely overcame my desire to win,” said the winner, Alfréd Hajós of Hungary.

In August 2008 in Beijing the women (who were not invited in 1896) had to swim much further: 10,000m, four laps. Against that, the lake was gently heated and chlorinated, and they made their own waves.

The result was a contest that combined, to an unusual degree, ferocity, comradeship and – in one case at least – raw courage.

The race was led from start to almost-finish by the British pair Keri-Anne Payne and Cassie Patten, who set the pace together. (Almost no story, then: British golds have become too routine to mention.)

But all the while the hot favourite Larisa Ilchenko of Russia, unbeaten since 2004, was in their wake, and at the final moment she struck, as they suspected she would. Ilchenko beat Payne by only 1.5 seconds, but it was a long 1.5 seconds.

“It’s not about swimming 10ks,” said the British coach Sean Kelly philosophically. “It’s about swimming the last 400m.”

At first sight this was a highly bizarre occasion, and the crowd seemed bemused. Waiting for the start in their one-pieces, the competitors looked like 1920s flappers from a black- and-white picture – having a dip at the lido before a night out at the roadhouse in Archie’s jalopy.

When they started, nothing was visible to the naked eye except a jumble of arms surrounded by a flotilla of official and media boats. It was as though scientists were tracking a shoal of rare giant fish. But it is the invisible element that creates the secret fascination of this race.

Instead of all that up-and-down stuff in lanes that constitutes normal Olympic swimming, this lot were in it together. And there was a great deal of what is known in rugby league as argy-bargy. Blocking is part of the strategy; kicking and thumping, especially when rounding the marker buoys, is illegal but routine. Ilchenko was in fact yellow- carded during the race for “intentional disruption” but, since she was busy at the time, she found out only afterwards.

All the while Ilchenko tracked the leaders. At one stage she was in company with a Chinese swimmer called Fang, increasing the sense of sharks closing in on their dinner. But the British strategy was well thought-out. They wanted to keep out of trouble, even though theory suggests it is a disadvantage to be in front where navigation is harder, and the still water offers more resistance. It was a long time before Ilchenko got her dinner.

Afterwards all the medallists embraced, and said nice things about each other. But they had a special word for the woman who came 16th. This was Natalie du Toit of South Africa, as fierce a competitor as anyone in the race, but with a difference: seven years ago her left leg was amputated below the knee. She burns with a passion to tell her story and inspire others. “I’m completely free in the water,” she says.

Du Toit also said it was “a dream come true” just to be here. They all say that, but in this case it really means something. She was asked if she would now be celebrating becoming an Olympian. Certainly not, she replied. She has six races in the Paralympics here next month.