Saunasaari, on Vasikkasaari island in Helsinki’s 300-island archipelago, opened June 26, 2026, with the city’s only public smoke saunas — heated without a chimney by a slate-lined pellet stove that fills the room with smoke before the fire is put out and the room vented for bathers. Its two smoke saunas hold more than 6,000 pounds of stones between them to keep the heat steady. Reach it by ferry from Helsinki’s Market Square.