Simon Turnbull: There's a Patten here. Open-water swimming is the 'new marathon'

Olympics Diary: We get to swim in some grotty water. Hyde Park is relatively clean and it's idyllic down there

Unlike Captain Matthew Webb, the first person to swim the English Channel unaided, Petar Stoychev has no plans to tackle the Whirlpool Rapids beneath Niagra Falls. Captain Webb lost his life trying to get the better of the treacherous waters there in 1883 – eight years after he gained worldwide renown for his historic feat of reaching dry land at Calais 21 hours and 45 minutes after setting off from Dover.

"I have no goals to do something like that," Stoychev said. "For me, swimming the English Channel is the most prestigious thing in open-water swimming, with all the history. It is the toughest. People compare it with climbing Everest. That was my goal. I wanted to be the first to do it in under seven hours."

The Bulgarian succeeded on 25 August, 2007. On the 132nd anniversary of Webb's maiden voyage, Stoychev swam the Channel in 6 hours 57 minutes – some 14 hours and 48 minutes quicker than the Shropshire sea captain who featured on the cover of Bryant and May matchboxes until recent years. It remains the only sub-seven-hour swim from Dover to Calais.

Stoychev will be back in British water tomorrow, riding the wave of mass-participation open-water swimming that has taken hold here since the introduction of the 10km marathon swim event at the 2008 Olympics. Stoychev finished sixth in Beijing and will not be the only Olympian among the 2,000-plus entrants for the British Gas Great East Swim at the Alton Water reservoir near Ipswich.

The event is the second in a series of five "Great Swims" organised by Nova International, the enterprising Newcastle-based sports events company headed by Brendan Foster, the 1976 Olympic 10,000m track bronze medallist, that stages the Great North Run, the world's biggest half-marathon, and the Great City Games Manchester street races that have featured Usain Bolt and Tyson Gay. The Great North Swim, which takes place at Windermere next week, from Friday 17 June to Sunday 19 June, has attracted more than 10,000 entrants.

Cassie Patten, the Cornishwoman who won Olympic bronze in the 10km swim in Beijing, is on the list for the elite mile races at Alton Water and Windermere. "I think the fact that open-water swimming has become an Olympic event has given it a credibility it didn't have before," she said. "I think Beijing and the success of myself and Kerri-Anne Payne and David Davies [both silver medal winners] has brought it more to the forefront in Britain and people are realising how much fun open water can be.

"I think it's just grabbed people's imagination – like marathon running did 30 years ago, and triathlon. It's something that's really challenging, that you have to train for. You can't just go in and do it."

For Patten, and for Stoychev, the one mile "sprint" at Alton Water tomorrow is a sharpener ahead of the main event of the year, the 6.2 mile marathon of the 10km at the World Championships in Shanghai in August. For the 24-year-old Briton and the 35-year-old Bulgarian, though, the second Olympic open water swimming competition is looming on the horizon. It takes place on the Serpentine in Hyde Park on Friday 10 August next year.

"I've been to Hyde Park a couple of times," Patten said. "It's going to be an amazing setting." The Serpentine Lake was created in 1730 when Queen Caroline, the wife of George II, ordered the damning of the River Westbourne. It achieved notoriety in 1816 when Harriet Westbrook, pregnant wife of Percy Shelley, drowned herself there.

"Thanks for that," Patten said. "I didn't know that. The thing with open-water swimming is there's always going to be history there, people who've been there first, and we get to swim in some grotty water. Hyde Park is relatively clean and it's such an idyllic area down there."