Kurogane Onsen

Kurogane Onsen in Nihonmatsu City, Fukushima Prefecture, rises at 1,400 meters within the national forest on the slopes of Kurogane-yama—Iron Mountain—in the Adatara volcanic range, accessible only by mountain trail and attached to the Kurogane Cottage mountain hut that serves hikers crossing the demanding Adatara ridge above the highland forests of former Iwashiro Province. The ferruginous and acidic waters carry the volcanic iron richness that gives the mountain its name, staining rocks around the spring in characteristic rust-red tones of iron oxide and providing a sharply invigorating, pore-cleansing soak at the end of a demanding alpine traverse through the volcanic highland. Earning access to Kurogane Onsen through mountain effort is considered by many Japanese hikers one of the most satisfying rewards in the alpine onsen tradition—the spring as a destination worthy of the physical demands of the journey to reach it.