Nanakura Onsen
Illustration photo — not a verified picture of this exact spot.
- Location
- Omachi, Nagano, Japan
- Water type
- carbonated
- Temperature
- 40 °C
- pH
- 6.3
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Mineralised water — eases movement and joints.
Nanakura Onsen is distinguished by a rare triple-mineral composition that combines bicarbonate, simple, and carbonated thermal waters in a single geothermal source, delivering a bathing experience that unites the skin-softening properties of alkaline bicarbonate chemistry with the effervescent tingling sensation of dissolved carbon dioxide. The coexistence of three distinct mineral types reflects the extraordinary complexity of the volcanic geology beneath this spring's location, where different mineral-rich layers intersect and blend before rising to the surface as a single, multifaceted thermal water. For onsen enthusiasts who seek the full diversity of Japan's geothermal mineral heritage within one bathing session, Nanakura Onsen's exceptional mineral variety makes it a particularly compelling and scientifically fascinating destination.