Japanese Forest Sauna Lets Trees Grow Through Its Timber Decks

Trees grow straight up through the floors of a new sauna in a Japanese forest. The Daichi Silent River Tree Sauna, designed by Daichi Inc, stands among the trees in Kanagawa, a prefecture (a region) southwest of Tokyo. The Dezeen design site has published the project's details.

The building has two stacked timber decks, which are wooden platforms, and a roof. The decks rest on timber grids that the trees help hold up. Small round holes are cut into the platforms, and the trunks pass through them. The central platform is partly supported by the slope of the ground beneath it.

The upper level holds the sauna room itself. Its walls are frameless glass, and inside there is a wooden bench and a central log burner. Apart from the sauna room and a small plunge pool, the decks are left open. Slim metal railings run along their edges. Wood and glass are the main materials.

Daichi Inc said the aim was to make the trees feel like part of the building. The existing trees were kept, and the studio used them as supports and as a defining feature of the space. The firm said the design is meant to create a physical sense of dissolving into the forest.

The sauna is one part of the Daichi Silent River retreat, which also includes guest cabins and more sauna spaces. The project has been shortlisted in the Leisure and wellness category of the Dezeen Awards 2026, according to Dezeen.