Earthboat Cave is a small timber accommodation quietly embedded in the lakeside forest of Shirakabako. The project was developed under the concept of "nature escape," an Earthboat philosophy that allows people to escape dense urban life and reconnect with nature in a calm environment.

Constructed entirely from Japanese cedar cross-laminated timber (CLT), the structure expresses warmth and solidity through the material. The interior surfaces are left exposed, allowing the cedar to age naturally and register the passing of time. Installed without foundations, the cabin touches the ground lightly, preserving the landscape beneath it and allowing easy relocation if needed.

The design was conceived around the idea of outdoor living. Rather than encouraging staying in an enclosed shelter, the cabin supports life that unfolds outside. A small sauna, directly accessible from the open air, offers warmth against the mountain chill, while the surrounding steps and fireplaces create places to gather and rest outdoors. The building serves as a quiet anchor, providing the comfort and security necessary to stay longer in nature.

Inside, the atmosphere is calm and tactile. The main window frames the lake at its most scenic point, turning the interior experience into an extension of the outdoors. The layout remains simple: a place to cook, rest, and observe. The interior is designed to be an extension of the outdoor experience. Light enters through multiple openings, shifting in tone throughout the day and reflecting the subtle changes in weather.

The architecture's quiet character defines its presence. It does not assert itself within the landscape but sits modestly among the trees, allowing nature to remain the dominant experience. Every element, from the sauna to the outdoor living area, is designed to enhance sensitivity toward the surroundings and to remind visitors of the rhythm of the natural world.

Earthboat Cave continues the Earthboat series, which explores how small, mobile CLT structures can foster new ways of hospitality within Japan's landscapes. Each is settled in its environment while sharing the same ethos of nature escape, offering moments to slow down and feel the quiet rhythms within the landscape.