Finnish saunas began as heated pits dug into slopes
A sauna is a room for dry or wet heat that makes bathers sweat. The Finnish word is ancient; Western forms grew from slope pits with fire-heated stones. Industrial stoves later pushed air toward 75–100°C, sometimes past 110°C.
Water on hot rocks yields löyly steam. Petri Kallio’s Germanic etymology links the word to a stack or heap of stones. Korean hanjeungmak stone domes appear in fifteenth-century Joseon records with royal health praise. Orkney stone houses may have held steam rooms, though that remains speculative. The oldest Finnish saunas were smoke saunas, where wood burned under a pile of rocks for six to eight hours before the smoke was let out, leaving heat for up to 12 hours. Sites in Greenland and Newfoundland have yielded structures much like Scandinavian farm saunas, with platforms and huge piles of scorched stones.
Finnish migrants carried the habit abroad; after World War II, Scandinavian and German regions embraced it—German soldiers had met Finnish saunas during the Continuation War. Chimneyed metal kiuas stoves replaced pure smoke saunas for many users. Finnish soldiers even built saunas in tents and bunkers. The electric sauna stove arrived in 1938 from Metos Ltd in Vaasa.
Such heat would normally be unbearable, so the trick is low humidity. Air, walls and benches stay above the dew point, while bathers' skin, at around 60 to 80 degrees, sits below it, so steam from the stones condenses on the body and releases heat. Humid steam baths such as the hammam run near 50 degrees instead, since wet heat at higher settings would scald. Higher benches are hotter, which lets bathers choose, and Russian bathers may wear a felt banya hat to shield the head.
Almost every Finnish house has a sauna, flats built since the 1980s often include one in the bathroom, and Helsinki's SkyWheel has one in a Ferris wheel gondola; Tampere's public Rajaportin Sauna dates from 1906. Guinness named the Koi Sauna at Sinsheim, Germany, 166 square metres and holding 150 people beside a koi aquarium, the world's largest. UNESCO lists Võromaa's smoke sauna tradition, added in 2014, and Finnish sauna culture, added in 2020, as intangible heritage.
Source: Sauna
