Kengo Kuma's 300,000-Brick Bathhouse Opens on Copenhagen's Paper Island

Kengo Kuma & Associates' KAI Water Culture House opens December 5th, 2026, bringing ten swimming pools to Copenhagen's Papirøen, better known as Paper Island. The 5,800-square-meter spa gives the city a new place to swim and bathe along a harborfront that has slowly shifted from industrial use to public recreation.

You can't miss the building. Five irregular brick towers rise above a continuous band of glass at ground level, their sloping walls forming a clustered silhouette along the quay. Gaps between the volumes open toward the sky. From the harbor, the heavy masonry seems to hover over the transparent base — an unusual lightness for such a monolithic structure.

How were the towers shaped?

Each tower takes its form from the pool beneath it, with every volume responding to its interior layout. Approximately 300,000 handmade bricks clad the angular surfaces, their varying gray tones echoing the surrounding harbor architecture. The masonry sits in a stepped pattern that gives the sloping walls a textured finish, especially where the surfaces catch changing daylight.

The facades hold 403 windows of different sizes. Some push daylight deep into the bathing areas; others frame views across the harbor. Inside, walls rise above the water at steep angles, forming tall bathing chambers that feel almost geological. The tallest volume, called the Culture Tower, will host cultural activities and community gatherings.

The signature move sits one floor up. The Valley Pool, an open-air basin, nestles between the five brick towers, so swimmers move through textured masonry with the sky directly overhead. The sheltered layout stays exposed to Copenhagen's weather — you can swim through rain, and even snowfall.

A heated outdoor onsen on the same level overlooks Copenhagen Harbour, drawing on Japanese bathing traditions while using the waterfront setting. Both outdoor pools run year-round, supported by a ground-source heat pump system tied to ten boreholes reaching 250 meters underground.

What's inside, and what comes next?

At ground level, KAI holds a 25-meter fitness pool, a teaching pool, and three smaller pools for children. Upstairs, warmer bathing areas join a cold plunge pool, with saunas and a steam bath rounding out the facilities. The transparent lower level opens views toward the water, connecting the swim spaces visually with the harbor.

Outside, a timber boardwalk will lead to designated harbor swimming and dipping areas overlooking the Royal Danish Playhouse and Opera Park. Those public facilities are expected to open in early 2027, following the building's December inauguration.

The project traces back to a city-led ideas competition in 2015, when Copenhagen residents submitted 160 proposals for Paper Island's future — most of them asking for a public swimming facility. Kengo Kuma & Associates won the architectural competition in 2017, working with Cornelius Vöge Atelier for Architecture during early design and Vilhelm Lauritzen Architects through detailed design and construction. MT Højgaard served as main contractor for the Paper Island Water Culture House Foundation.

Nearly a decade on, the finished building delivers what residents asked for at the harbor's edge.