Canal plus The quest to make urban waterways swimmable

Around the world, architects and campaigners are turning previously polluted rivers and harbours into bathing spots

- Oliver Wainwright

On a summer morning in the Swiss city of Basel, groups of commuters bob merrily down the Rhine. They're not on boats but in their trunks, clutching fish-shaped waterproof bags that double as floats as they drift to work alongside cargo ships.

At lunchtime in Copenhagen, the harbour walls are packed with bronzed bodies tanning on tiered decks, and launching themselves into the water from daring wooden platforms. After work in Vienna, the grassy banks of the Danube throng with swimmers lounging in the dappled shade.

After a century of ignoring the very arteries that allowed them to grow in the first place, cities are learning to love their rivers again. Around the world, as global heating causes summer temperatures to soar, people are reclaiming urban waterways.

Last month, the urban swimming movement made its biggest splash yet, when 110 athletes dived into the River Seine for the Olympic triathlon. The televised spectacle of swimmers frontcrawling their way through Paris, flanked by beaux-arts bridges, offered a glimpse of what all our urban waterways could look like. Could taking a plunge in the Thames, Hudson or Tiber one day be as common as going for a stroll in the park?

"What's happening in Paris represents a generational baton change," said Matt Sykes, an Australian landscape architect and the convener of the Swimmable Cities Alliance, a global network of urban swimming campaigners. "The next generation are ready - kids will be watching the Olympic triathlon on TV and asking: 'Why can't we swim in our river?""