Yumoto Onsen Iwaki
- Location
- Yumoto, Iwaki, Fukushima, Japan
- Water type
- sodium chloride
- Temperature
- 45 °C
- pH
- 7.3
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Dense, salty water — you float without effort.
Yumoto Onsen Iwaki is located in Iwaki City, Fukushima Prefecture, one of the most extensive municipalities in Japan, stretching from the Pacific coast to the Abukuma highlands in a vast territory encompassing fishing villages, coal mining ghost towns, agricultural plains, and mountain forests in one of Tohoku's most geographically diverse cities. The chloride-rich thermal waters of Yumoto Onsen have been flowing for over a thousand years and are recorded in 10th-century historical texts — making Yumoto one of the Three Ancient Hot Springs of Tohoku (Oshu Sandai Onsen) alongside Tsuru-no-yu in Akita and Kaminoyama in Yamagata. The spa town's position on the Joban Coal Mining Railway corridor, in a landscape still marked by the legacy of the Joban coalfield that powered Tohoku's industrial development, and its proximity to the Pacific coastline dramatically altered by the 2011 tsunami, gives Yumoto Onsen a history spanning ancient thermal tradition, industrial boom, and post-disaster renewal of extraordinary depth.