Aso Nishiyu Onsen

Aso Nishiyu Onsen is located in Aso City, Kumamoto Prefecture, on the western flank of the Aso caldera — one of the world's largest active calderas, measuring 25 kilometers across, within whose vast interior an entire farming civilization has developed at the foot of still-erupting Mount Nakadake. The siliceous waters here carry the mineral signature of one of Japan's most active volcanic systems, bathing visitors in waters born of geothermal processes that have shaped this extraordinary landscape for hundreds of thousands of years. Open-air bathing at Aso Nishiyu Onsen with views of the volcanic crater complex and endless caldera grasslands represents one of Japan's most geologically dramatic hot spring experiences.