Kawarayu Onsen; Oyu
Naganohara, Gunma, Japan
- Location
- Naganohara, Gunma, Japan
- Water type
- sulfurous
- Temperature
- 45 °C
- pH
- 6.5
Water profile
Thermicity
Sedative
LowHigh
Relaxing — deep, immediate muscle release.
Mineralisation
Bio-active
LowHigh
Rich in active gases or metals — a strong mineral character.
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
SoufreSulfuresSulfates
Kawarayu Onsen, known as Oyu, is a hot-spring bath in Naganohara, in the mountains of Gunma Prefecture. Its sulfurous water is among the hottest in this selection, at 45°C, shared between an indoor bath, an outdoor rotenburo and a sauna.
Insider tip — Kawarayu is one of the oldest hot springs in the Agatsuma Valley, historically threatened by the Yamba Dam project before it was ultimately completed in 2019. The powerful sulfurous spring carries the same volcanic energy as the nearby Kusatsu resort and the outdoor Oyu communal bath retains a wonderfully archaic character.
Nearby
Frequently asked questions
How hot is the water?
The water runs quite hot here, around 45 °C — a sedative water that brings immediate muscle release.
What type of water is found here?
This spot features sulfurous water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.