An even bigger splash: swimming across London

Fifty hardy souls in swimsuits, hats and goggles, gather at Tooting Bec Lido in south London at 5.30am. They swim one length of that lido, then at two others, 10 pools, and two lakes, and finish, 14 hours later, at Hampstead Heath Mixed Ponds in the north of the city. They are transported, between swims, by a decommissioned Routemaster bus. They are required to run through crowded streets, on a cold July day, wearing very little. Their every movement is recorded by a film crew.

These are the bare facts of SWIm. But they do not begin to convey the cosmic oddness of the event. This is "live art" as conceived by Amy Sharrocks, 37, an artist with an interest in Londoners' relationship with water. Last year, she created Drift, a piece where, over two nights, the artist invited punters to join her in a boat in a public swimming bath in Camberwell.

Next year, Sharrocks will walk on the paths of London's underground rivers - the Fleet, the Effra, the Westbourne et al - and "explore their relationship with the roads that have replaced them as passageways".

This year, it was the turn of SWIm, an art project inspired by John Cheever's short story "The Swimmer" - a tale of a disenchanted suburbanite swimming through his neighbour's back yards - and the ensuing film starring Burt Lancaster.

SWIm doesn't feel like art. It feels like a deranged school excursion. Still, that didn't stop 50 of us from signing up. I, at least, had the excuse of covering the story. But who were the other Speedo-clad dolts?

As it turns out, they were a collection of doctors, artists, writers, company directors, campaigners and IT geeks. They were old and young, fat and thin. They had signed up because they thought it might be "a laugh", a "journey", or a "unique opportunity". Some gloried in the term "Great British Eccentric". Some were worried their workmates might see them. But all of them loved to swim.

The toughest of these swimming nuts may have been disappointed, because SWIm involved very little swimming. One length each of 15 pools - including the 90m Tooting Bec Lido, Europe's largest freshwater pool - spread over a day, is a breeze for people who could knock out 15 lengths of Tooting Bec before breakfast. But SWIm, as the foolhardy 50 would discover, was much more than a work-out.

We breakfasted at 5.30am on croissants and apple juice. My second croissant made a brief, haunting reappearance at 6.15am, 60m down Tooting Bec Lido. Still, 50 breakfasts and 50 swimmers arrived, intact, at the shallow end. SWIm had begun. What followed would become a familiar routine. Run back to the bus. Dry off. Have a natter. Stop the bus. Run down a high street. Find the pool. Swim a length. Repeat.

If you think this continual dipping would become repetitive, you'd be right - but not until well after lunch. During the morning, there was something novel, light-hearted even, about our endeavours. We visited 1930s architectural classics, such as the glorious Brockwell Lido; we ate bacon sandwiches; we scared commuters on their way to work.

There was one joyous moment at 7.15am, when a businessman in Balham was confronted by 50 semi-naked pedestrians in swimming hats outside his front door. "Hello!" said one swimmer, but the businessman didn't hear. Or, at least, he didn't want to. The only way his brain could compute what his eyes were seeing was to ignore it. And so, briefcase in hand, he lowered his head and pushed his way through the swimmers as if we were an inconvenient crowd at a Tube station.

These street-level adventures were good conversational fodder on the top deck of the bus, where the eclectic clutch of travellers exchanged stories. Michael Waldman, 50, makes television documentaries. He goes nowhere without his trunks, swims in mountain lakes in his holidays, and once backstroked across Venice's Grand Canal at midnight for a packet of cigarettes. Waldman joined SWIm because he saw an advertisement in Time Out, and was interested in "the idea of this as a bit of art: possibly a bit wanky, but possibly rather wonderful".

"I regret the demise, and closure, of pools," he says. "I don't see this event as particularly a campaigning thing, but I do regret that politicians don't recognise the importance of swimming pools. So anything that celebrates swimming is a good thing. It's my drug. It's much more than exercise. I wouldn't call it spiritual, but it definitely lifts the spirits. In fact, I'd love to be doing more swimming today, but I understand why we can't."

Over a bacon and egg sandwich at the Brockwell Lido, Sally Goble, 41 - who, last year, swam the English Channel - says she is also sanguine about the lack of real swimming opportunities. "I joined for the event as well as the swimming," she says. "The thing I like about this, is, so often, when I've been working, I'm rushing to get to a pool before it shuts. It's half an hour there and half an hour back to get that precious 15 minutes before the pool closes. I think [SWIm] is a bit like that. There's loads of travelling for very short swims. It's a microcosm of my life.

"Also, I do have swimming friends, but generally I'm at work with a lot of people who aren't into swimming. It's great to be with a bunch of random people you don't know anything about, apart from they are really into swimming. We can share a passion, and that's great. It is a weird event. It's eccentric - but swimmers are quite eccentric, generally."

Sharrocks has decided, evidently, to tap into this eccentricity, when our bus parks up on the south side of Vauxhall Bridge, and we are encouraged to run across the Thames in our smalls. By now, there are some who are relishing the wackiness, and some who are happy to go along with it to keep the peace. What MI6 must think of us as they stare down from their Lego base is anyone's guess, but a builder in Victoria make his feelings known. "Get your kit on!" he bellows. It becomes something of a bus catchphrase.

One man who has no need to get his kit on is Chris Morris (not he of Brass Eye fame), a fine physical specimen whose moustache and upright posture make him look like a Second World War fighter pilot. For Morris, an osteopath based in Reading, SWIm is just one momentous event in a week which included his 60th birthday and the arrival of his first grandchild.

"I've swum all my life, but more seriously over the past decade," says Morris. "I initially did it only in pools, until I went on a brilliant swimming holiday in the Greek Cyclades islands, and I thought, 'man, this is so much better than ploughing up and down a pool!' I recommend swimming to my patients, and it's well known now that cold water swimming can have excellent effects on your circulation - and I sort of practise what I preach. I fell in love with Tooting Bec Lido a few years ago. I heard about this event via their website, and I knew I had to do it."

At noon, we arrive at the ring-fenced swimming area at the Serpentine in Hyde Park. The swimmers, by now inured to the ritual humiliation of walking through public spaces dressed only in intimate apparel, have a new challenge: how to keep their mouths closed for 70m while swimming across a boating lake, while simultaneously avoiding the surly geese. Not everyone meets the challenge. After a thrash across the moss green course, there is a dash for the solitary outdoor shower to expunge the feathers and goose poo from our shivering torsos. Afterwards, Sharrocks explains why she dragged us all out of bed for this punishment. "We're doing this for the dream of swimming London," says the artist. "And we're doing this for broader access to live art. And we're doing this for greater access to water in London. I've really loved how everyone's trepidation at the start dissipated as soon as we got into the swim, and there is this great sense of freedom."

The great sense of freedom soon melds into a great sense of lethargy, as sugar levels wane in the post-lunch period. We are now knocking out lengths of small, indoor pools, and the romance of the early, outdoor adventures has all but disappeared. We swim the Seymour Leisure Centre in Marylebone, the Portchester Centre in Bayswater, and the Jubilee Centre off the Harrow Road.

Sometimes, we stop when there are no pools. In Little Venice, the stern Irish project manager tells us we must leave the bus, just for a run along the side of the canal. We comply, but, with no designated swimming area, the trip is pointless. In a bid to infuse the jog with meaning, some decide to swim the canal. Led by Waldman, who has form with this sort of behaviour, half a dozen of the braver swimmers jump in, to discover, "six feet of dirty water, and six feet of shit." The canal-jumpers are told to take a thorough shower before their next swim.

The sequence of indoor, chlorinated baths is next interrupted in St. John's Wood, where, having just passed Lord's cricket ground, we find ourselves at a plush looking block of flats. We troop round the back of the apartments and find a swimming pool that could comfortably double as a foot-bath. Somehow, all 50 swimmers crowd in, do handstands, whoop and holler, and then leave for the bus. It's another odd punctuation mark in an odd afternoon.

Luckily, it's the last bum note. As the sun comes out in the late afternoon we swim at Parliament Hill Lido, with its gleaming stainless steel refit, and the mossy, endangered Hampstead Heath Ponds. At the conclusion of the last swim, the overwhelming sensation is elation: not that we have overcome a mighty obstacle, but that we have contributed to an unrepeatable event. Was it art? Who knows. But we do know the answer when somebody shouts: "Anyone want another crack at Tooting?"