Perched at the north-west edge of a private island, the Grotto Sauna is a sculpted space, a sensual experience, and a sophisticated exercise in building science. When PARTISANS met on site, they knew that their most prominent challenge was to make a free-standing structure that not only respected, but also matured from the context. Contemplated research was conducted, and through the process a Grotto was set as an inspiration that would inform the design. Grottos, historically, have been known as natural or artificial caves that are embedded deep behind the curvature of streams, and thus discovered by those who would take the time to explore.