KAI, Copenhagen’s new water culture house, is set to open on 5 December on Paper Island, bringing 10 swimming pools, three saunas, an outdoor onsen and direct access to designated swimming areas in the harbour.
Designed as part of the wider effort to transform Copenhagen Harbour into a cultural and recreational waterfront, the 5,800-square-metre facility will combine swimming, wellness and cultural activities in one complex. It will also give residents and visitors more opportunities to enjoy the city’s waterfront, regardless of the weather.
The project is designed by Japanese architecture firm Kengo Kuma & Associates. Its name draws on two languages: “kai” means sea in Japanese, while “kaj” is the Danish word for quay. Both references reflect the building’s relationship with the water and its location on Paper Island.
KAI is described as a “water culture house”, a concept that extends beyond conventional swimming facilities. In addition to its indoor pools and wellness spaces, the complex will provide access to designated harbour swimming and dipping zones, alongside cultural experiences intended to encourage people to engage with water in different ways.
The development is part of Copenhagen’s continuing transformation of its Inner Harbour, which has gradually shifted from an industrial port into an area for public recreation, culture and leisure.
Yuki Ikeguchi, lead architect and partner in charge at Kengo Kuma & Associates, said the building was conceived as a public institution that would connect water, architecture and community life.
She described KAI as a cultural cornerstone of Paper Island, with the ambition of making physical and mental wellbeing a more natural part of everyday life in the city. The design also places the building within the wider harbour environment rather than treating it as an isolated leisure complex.
The architecture consists of five brick towers, each shaped according to the outline of the swimming pool beneath it. The arrangement gives the building a distinctive form while organising its different swimming and wellness facilities across several levels.
On the ground floor, visitors will find a 25-metre fitness pool, a teaching pool and three children’s play pools. This level will also provide access to the outdoor harbour bathing areas. These include a designated swimming zone with views towards Opera Park and a separate plunge area overlooking the Royal Danish Playhouse.
The first floor will focus on relaxation and wellness. Its facilities include a therapy pool, a hot pool and a cold plunge pool, offering different temperatures and bathing experiences. There will also be an open-air valley pool and an outdoor Japanese-style onsen, where visitors can enjoy warm-water bathing while looking out across the harbour.
Beyond the pools, KAI will have three saunas, a heated stone facility and a steam bath. The complex is designed to accommodate up to 380 bathers at a time, making it a substantial addition to Copenhagen’s public swimming and wellness facilities.
Its combination of indoor swimming, outdoor bathing, sauna experiences and direct harbour access reflects the project’s broader ambition to make water a central part of public life on Paper Island. Rather than functioning solely as a swimming centre or spa, KAI is intended to bring several aspects of Copenhagen’s waterfront culture together under one roof.
With its opening scheduled for 5 December, the new facility will add another major public attraction to the city’s evolving harbour district.
