Iwakura Onsen

Iwakura Onsen is a hot spring in Ome City, western Tokyo Metropolis, billed on its official website as the only hot spring resort within the Tokyo Metropolis, providing bicarbonate and ferruginous mineral bathing to residents of the vast metropolitan area who seek thermal wellness without traveling outside the city boundaries, though as of 2022 only a single inn facility remains operational at the spring. Ome City occupies the western reaches of Tokyo Metropolis along the Tama River valley, bordered by the mountains of the Chichibu-Tama-Kai National Park, and it preserves a distinctly rural character that contrasts sharply with the urban density of central Tokyo, offering hiking trails, river activities, and traditional crafts alongside the hot spring tradition. The iron-bearing bicarbonate waters of Iwakura Onsen carry the distinctive reddish tinge of ferruginous mineral waters and are valued for their tonic properties in addressing fatigue and circulatory weakness, providing a medically meaningful bathing experience within the surprising geographical extent of the Tokyo Metropolis.