It is an afternoon session at Sheffield's council-run Ponds Forge pool, and the usual flotilla of keep-fit swimmers is determinedly groping its way up and down the lanes.
But across the 50 metres of azure water, an impossibly toned group of young Americans are popping dives of dizzying complexity and athleticism.
The USA Olympic diving team has just arrived in South Yorkshire – the first group of elite athletes to arrive at their pre-Games training camp in readiness for London 2012.
The various national teams' training camps will be scattered across Britain, from Plymouth to Glasgow, via such towns as Tonbridge, Knowsley and Ipswich. For many people, local leisure centres and sports fields offer a great chance to see the world's finest athletes (and those who just try hard) in action.
At Forge Ponds yesterday there was considerable excitement – as well as some nonplussed regular swimmers. Scouts, sea cadets, children on half-term and, of course, the city's own aspiring young divers, came to watch the Americans train and to enjoy a spot of one-on-one coaching as part of the team's ongoing diplomatic mission to promote their sport. The US divers included the gold medal hopefuls Troy Dumais and David Boudia, who were honing their fitness ahead of next week's Olympic qualifiers in London.
Boudia, 22, from West Lafayette in Indiana, knows one of his main rivals this summer is likely to be Britain's Tom Daley. But since the advent of Chinese domination of the sport, he knows that either will be lucky to walk away with the ultimate prize.
"It has always been my dream to be an Olympian," he said. "Success is down to a lot of different things. First you have to overcome that fear of the 10m board. It takes a lot of physical endurance and a lot of mental endurance. You need the willingness and the drive to pursue your dream."
Among those lapping up this inspirational advice were Ross Haslam, 14, and 11-year-old Channein Lancaster, who have been diving with Sheffield's elite development team since they were little and are among its brightest hopes. Like others in the squad, they train for 18 hours a week – splitting their time between the pool and the gym.
"Some of our friends say, 'why do you dive?' They say 'why don't you come out with us?'," said Ross. "We tell them it is because we want to do it."
Sheffield has embraced the potential of the Olympics and will host four teams before the Games. The city continues to style itself a centre of English sport despite its financially disastrous staging of the World Student Games in 1991. Yet Sheffield estimates it will benefit by £19m from this summer's event after spending £1m to lure teams to share its world-class facilities. "It was not a bad return on our investment," said Steve Wilson, a city councillor. "It just shows that a city 170 miles from London is benefiting from the Olympics."