【Shibu no Jigokudani Geyser】
The Shibu no Jigokudani geyser is a symbol of Nagano Prefecture’s hot spring culture and a rare geothermal phenomenon. Unlike most geysers, which erupt at intervals ranging from a few minutes to several hours, it emits a continuous plume of water that can reach 20 meters in height and exits the riverbed at more than 90 degrees Celsius. The water is rich in sodium, sulfur, and calcium sulfate, and crystalline mineral deposits that accumulate around the geyser’s mouth must be periodically removed to ensure it does not become blocked.
Jigokudani (literally, “hell valley”) is a name that is often given to areas with widespread geothermal activity. Before the source was tapped for use as bathwater, Shibu no Jigokudani had many geysers that filled the valley with rumbling sounds, clouds of steam, and whiffs of sulfur. Even today, it is easy to see how it evoked visions of the underworld.
On the opposite side of the Yokoyu River is Kōrakukan, a historic inn established in 1864. Its riverside baths provided the inspiration for the popular monkey bath at Jigokudani Wild Snow Monkey Park. Young monkeys sometimes played in Kōrakukan’s baths, and to discourage this behavior park officials decided to entice them away from the inn with a private bath of their own. Over time, the monkeys living in the area developed their own bathing culture.
