Built directly into a 751-year-old lava flow in the Reykjanes UNESCO Global Geopark, the Retreat encompasses a subterranean spa, geothermal lagoon, a restaurant and a 62-suite hotel encircled by the Blue Lagoon’s seawaters. Days were spent exploring the site, letting cracks and fissures reveal how to best lay out the program. Interesting lava formations were encountered during earthwork, compelling us to make revisions to our plans in order to incorporate these unexpected features. To a degree, groundwork was simultaneously final interior finishing and landscaping. This process was antithetical to the typical mode of working, where changes and experimentation during construction are generally undesired. Improvisation was fundamental to the Retreat’s unique design process, requiring everyone; designers, client and contractor to share the same patient, respectful vision. Treasures of the site, the mineral-rich water, the rugged lava and centuries old moss, become the focus point of every space in the building, aiding in the psychological renewal of its users. The Retreat is predominantly made of concrete. The concrete varies from textured off-white in the lobby to smooth, dark grey in the depths of the spa, echoing the lava walls. Perforated facades and interior screens evoke the natural patterns that emerge when the air pockets locked inside lava rocks are revealed. Dark terrazzo floors were created using local lava. Wood is juxtaposed with concrete and lava surfaces to establish an authentic, inviting atmosphere. The subtle profusion of tactile, natural materials penetrates every detail, producing a realm of deep comfort inspired by the landscape.