Nigorigawa Onsen (Nagano)
- Location
- Achi-mura, Nagano, Japan
- Water type
- sulfurous, calcium-rich, silica
- Temperature
- 43 °C
- pH
- 6.5
Water profile
Relaxing — deep, immediate muscle release.
Rich in active gases or metals — a strong mineral character.
Soft water — natural, classic buoyancy.
Nigorigawa Onsen in Nagano Prefecture takes its name from the turbid, mineral-heavy waters that give the spring its distinctive visual character—nigori meaning cloudy or murky, a quality in Japanese onsen that signals exceptional mineral concentration and therapeutic potency beyond what clear springs can offer. The combination of sulfated, sulfurous, and siliceous waters creates a mineral profile of remarkable complexity, delivering the joint-soothing properties of sulfates, the detoxifying character of sulfurous compounds, and the skin-softening silica that characterizes Japan's most celebrated beauty springs. Set in Nagano's thermally active mountain landscape, this spring represents the full mineral richness of Japan's volcanic spring tradition.