Zao Onsen
- Location
- Yamagata, Japan
- Water type
- carbonated, acidic
- Temperature
- 55 °C
- pH
- 2.8
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Mineralised water — eases movement and joints.
Zaō Onsen is a celebrated mountain hot spring resort located on the slopes of Mount Zaō in Yamagata Prefecture, on the main island of Honshū in northern Japan. The thermal waters are notably acidic and carbonate-rich, with a distinctive jade-green hue that gives the outdoor pool its extraordinary visual character, set dramatically against the volcanic mountain landscape. In winter, Zaō becomes world-famous for its 'juhyo' or snow monsters — towering spruce trees encased in fantastical sculptural forms of ice and snow sculpted by the mountain's unique weather patterns. Whether visiting for the vivid volcanic waters in summer or the surreal winter landscape, Zaō Onsen offers one of Japan's most visually dramatic and atmospherically memorable onsen experiences.