Earthboat Cave is a compact timber mobile cabin hotel designed to sit quietly within the lakeside forest of Shirakabako, Nagano Prefecture. Conceived under the Earthboat concept of “nature escape,” the project explores how architecture can offer comfort while remaining humbly within the landscape. The structure is built entirely from Japanese cedar cross-laminated timber (CLT). Its material presence is both structural and atmospheric — a single substance forming floor, wall and ceiling. The surfaces are left uncovered, allowing the cedar to age and absorb the changing tones of its environment. The building is installed without foundations, minimising impact on the site and allowing the ground to remain as is. From the exterior, the cabin sat quietly among the trees. An iconic opening faces the lake, framing the surrounding scenery rather than announcing the building itself. Inside, the warm, continuous wood creates a sense of stillness. The plan is compact but complete — a place to rest, cook, and watch the changing light. The sauna, accessed directly from outside, forms part of the daily rhythm, connecting warmth and air, interior and landscape. The project’s calm character comes from its lack of assertion. Instead of projecting into the environment, it sits back, allowing the landscape to lead. The outdoor living area extends this idea — not as a spectacle, but as a quiet space where one can remain in the open, listening and observing. Earthboat Cave continues the evolution of the Earthboat series, which develops small, relocatable CLT accommodations across Japan’s varied terrains. Each is tailored to its site while sharing the same ambition: to create architecture that coexists with nature through modesty, precision, and calm - allowing people to "escape" into nature.