Copenhageners already swim in their harbour year-round — even in winter, even in snow. From 5 December they'll have somewhere considerably more comfortable to do it. KAI, a new "water culture house" on Paper Island, opens its doors in early December as part of the city's ongoing effort to turn its old industrial port into a living, swimmable waterfront.
The building itself is a draw. Japanese studio Kengo Kuma & Associates designed the complex as five brick towers, each shaped to match the outline of the pool beneath it. The name works in two languages: "kai" is Japanese for sea, while "kaj" is Danish for quay — a neat nod to the building's position on the Inner Harbour. Lead architect Yuki Ikeguchi describes it as a civic institution dedicated to water and community, wrapped in a public harbour bath.
Inside, it's substantial: around 5,800 square metres with ten pools and capacity for 380 bathers at once. The ground floor is the sporty end, with a 25-metre fitness pool, a teaching pool and three children's play pools, plus direct access to harbour swimming areas — one zone overlooks the Opera Park, another the Royal Danish Playhouse.
Head upstairs for the wellness floor, which sounds like the real treat: a therapy pool, hot pool and cold plunge, an open-air "valley pool" and an outdoor onsen with harbour views. There are also three saunas, a steam bath and a heated stone. Expect cultural programming too — the team behind it says the house will host experiences that invite people to explore water in new ways.
For travellers, KAI lands at an interesting moment for Copenhagen. The Inner Harbour has become one of Europe's most surprising swimming spots, clean enough for open bathing right in the city centre. A day here could easily combine laps and saunas with a wander around Paper Island, a short walk from Nyhavn, the Opera and the Playhouse. It's also a rare excuse to try a Danish winter bath: plunging into cold harbour water straight from a hot sauna is very much a local ritual, and December is exactly when it comes into its own.
Whether you're a design fan, a sauna devotee or simply travelling with kids who need burning off on a rainy day, this is shaping up as one of Copenhagen's more useful new openings — indoor comfort and outdoor swimming rolled into one waterside address.
