Copenhagen gave its cleaned harbour back as free public baths — and swimming caught on

Thirty years ago Copenhagen's harbour was a polluted mess of sewage and industrial waste. The city spent roughly a decade cleaning it, the EU officially declared the water clean in 1999 — and then Copenhagen did what few cities did: it opened the water to citizens instead of treating it as mere infrastructure. In 2002 the first free public harbour bath opened at Islands Brygge, designed by then-little-known architects Bjarke Ingels and Julien De Smedt.

The design was simple and audacious: timber pools and diving platforms floating in the inner harbour, free for anyone, with wading shallows and a water's-edge feel that makes the bath read as a beach rather than a pool hall. The baths were an instant success; on sunny days Copenhageners flock to them, and in winter clubs keep swimming in the cold water.

The city kept going — a second bath followed a year later, a third opened in Sluseholmen in 2012 — and keeps the water swimmable with basins that hold 260,000 m³ of wastewater so rain spills never enter the harbour, with quality monitored through a dedicated app. Today the harbour offers 14 bathing areas: three harbour baths, ten official swimming zones, three beaches and a 450-metre open-water swim lane.

The idea travelled. The 2002 bath 'launched a generation of increasingly expressive timber platforms', and Denmark is cited as leading the global swing toward city swimming — Paris spent €1.4bn cleaning the Seine ahead of the 2024 Olympics, Budapest campaigns to bring floating pools back to the Danube, and in 2019 CNN named Copenhagen the best city in the world for swimming.