In a Kanagawa forest, living tree trunks rise through the timber platforms of a sauna. Daichi Inc, a Japanese architecture studio, designed the Daichi Silent River Tree Sauna, a kanagawa forest sauna, to sit among the trees rather than clear space for them.
The site lies southwest of Tokyo. This japanese sauna forms part of the Daichi Silent River retreat, which also includes guest cabins and additional sauna spaces.
Trees as structure
According to Daichi Inc, the studio wanted the trees to feel “part of the architecture itself.” The trees act as both supports and the main visual feature of the pared-back structure.
Timber that lives with its surroundings also shapes Casa Celeiro, where a large wooden retreat sits quietly in its landscape. Casa Celeiro’s Timber Retreat Embracing Minas Gerais Nature shows another way to let wood and setting work together.
The studio contrasts this approach with conventional building. In its account, standard architecture typically clears nature away, cutting down thick, strong trees and turning them into standardised building materials.
“In this project, the existing trees were preserved and used directly as part of the spatial framework,” the studio said. The aim was to blur the boundary between nature and the built environment.
The project has been shortlisted in the Leisure and wellness category of the Dezeen Awards 2026.
How the kanagawa forest sauna is built
The structure consists of two stacked timber decks and a roof. The central platform rests partly on the site’s natural slope.
Thin planes sit on timber grids, which the trees themselves support. Small circular cut-outs in the planes let the trunks pass through.
Timber steps link the platforms. The highest level holds the central sauna room, enclosed in frameless glass. Inside, a wooden bench faces a central log burner.
Apart from the sauna room and a small plunge pool, the decks are open and flexible. Slender metal balustrades run along their edges.
Wood and glass are the primary materials. The studio says the existing trees were integrated into the architectural framework, not added as decoration.
Architecture that coexists with the forest
“Rather than placing architecture on top of nature, the project allows architecture to coexist with it,” the studio said. The result, it argues, is a bodily experience in which visitors feel they are dissolving into the forest.
The studio also said the decks and sauna spaces were positioned to appear to float within the trees. “The forest is not treated as a backdrop, but functions as an essential structural part of the architecture,” it said.
Other recent forest saunas on Dezeen take a similar material approach. Puusauna in Finland, designed by architect Jaakko Torvinen, rests on whole charred tree trunks taken from the neighbouring forest. An off-grid bathhouse in London also appeared on the site recently.
Forest saunas are becoming a recurring theme, and a Slovakian example takes a similarly gentle approach to its site. Slovakia’s Eco-Friendly Sauna Melding With Nature is worth a look for its timber-led take on blending into the landscape.
The Daichi Silent River Tree Sauna shows that a building can carry its load on the forest it stands in. Its trees are not removed to make room for the sauna. They hold it up.
H/T dezeen.com
Frequently asked questions
Who designed the Daichi Silent River Tree Sauna in Kanagawa?
The Daichi Silent River Tree Sauna was designed by Daichi Inc, a Japanese architecture studio. It is located in a Kanagawa forest, southwest of Tokyo.
How do the trees support the Kanagawa forest sauna’s structure?
The existing trees were preserved and used directly as part of the spatial framework, acting as both supports and the main visual feature. The thin planes sit on timber grids that the trees themselves support, and small circular cut-outs let the trunks pass through.
What materials were used to build the Daichi Silent River sauna?
Wood and glass are the primary materials of the sauna. The central sauna room is enclosed in frameless glass and contains a wooden bench facing a central log burner.
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