Iide Soegawa Onsen

Iide Soegawa Onsen emerges along a tributary of the rivers draining the Iide Mountain range—a remote volcanic massif straddling the borders of Yamagata, Niigata, and Fukushima prefectures—where sulfated thermal waters arise from deep geological formations beneath one of Japan's most pristine wilderness areas. The Iide Mountains are celebrated among serious hikers for ancient beech forests, alpine flowers, and near-total absence of tourist infrastructure, making a thermal spring here a true backcountry discovery for those willing to venture deep into the wilderness. The sulfate minerals in the water make for a soothing, relaxing soak, a welcome reward after the demanding alpine terrain surrounding this remote spring.