A modern Finnish sauna A sauna (/ˈsɔːnə, ˈsaʊnə/,[1][2] Finnish: [ˈsɑu̯nɑ], Estonian: [ˈsɑu̯n]) is a room or building designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these facilities. The steam and high heat make the bathers perspire. A thermometer in a sauna is typically used to measure temperature; a hygrometer can be used to measure levels of