Koshibu Onsen
Achi-mura, Nagano, Japan
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- Location
- Achi-mura, Nagano, Japan
- Water type
- bicarbonate
- Temperature
- 40 °C
- pH
- 8
Water profile
Thermicity
Sedative
LowHigh
Relaxing — deep, immediate muscle release.
Mineralisation
Restorative
LowHigh
Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
BicarbonatesSodiumCalcium
Koshibu Onsen is located in Achi-mura, Nagano Prefecture. Its bicarbonate waters, at 40°C, are available in an indoor bath and an outdoor rotenburo, with a sauna on site, deep in the mountains.
Insider tip — Achi-mura (Achi village) in the Kami-Ina district of southern Nagano is famous for having the highest stargazing frequency of any village in Japan — on clear nights above the Ina Valley fog, the Milky Way blazes in spectacular clarity from this mountain village at 900-1,900 metres. Koshibu Onsen on the Koshibu River draws on bicarbonate springs of this clean-air highland, where mineral bathing and extraordinary star-gazing combine in one of Japan's most astronomically exceptional landscapes.
Nearby
Frequently asked questions
How hot is the water?
The water runs quite hot here, around 40 °C — a sedative water that brings immediate muscle release.
What type of water is found here?
This spot features bicarbonate water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.