Okuoku Hachikuro Onsen
Kosaka, Akita, Japan
- Location
- Kosaka, Akita, Japan
- Temperature
- 45 °C
- pH
- 3.5
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
Okuoku Hachikuro Onsen, in Kosaka, Akita Prefecture, emerges at 45°C with sulfurous, acidic water (pH 3.5), typical of northern Japan's volcanic springs. An indoor bath, an outdoor rotenburo and a sauna are on offer.
Insider tip — Deep in the Hachimantai volcanic zone near Kosaka, a former copper and zinc mining town in Akita. The acidic, sulfurous waters reflect the area's rich mineral geology. 'Okuoku' means 'deep inner valley' — expect a wild, atmospheric setting far from any crowds.
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 & acidic water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.