Two brothers have created the world's first hot-air balloon sauna. Ari and Jari Lehtinen, 57-year-old twins known for their unconventional sauna designs, have successfully launched their latest creation, which combines Finland's love for saunas with aviation . The innovative flying sauna, weighing just 170 kg, ascended to an altitude of 2,300 metres during its inaugural flight, allowing its occupants to experience temperatures of 80 degrees Celsius while floating above the Finnish landscape.