Onneto Yunotaki Falls is a hot-spring waterfall south of Lake Onneto.
Warm water flows 30 meters down over moss-covered volcanic rock at the falls. The upper pool used to be a popular outdoor bathing spot, but bathing has been prohibited since deposits of manganese oxide were discovered there.
Microbial algae and bacteria in the hot water oxidize manganese minerals, creating black deposits of manganese. This type of manganese ore, normally found only at the bottom of the ocean, is used to produce iron and dry cell batteries. Onneto Yunotaki Falls is designated a Natural Monument of Japan for being one of the only places on Earth where manganese ore deposits can be found above ground.
To access the falls, take the 1.4-kilometer Onneto Yunotaki Falls Trail from the southern end of Lake Onneto. The path is wide and flat, and easy to walk. Along the way, you may encounter Eurasian red squirrels, Japanese deer, and a variety of wild birds. Beware of bears, and use a bear bell or make noise while walking.
The path to the waterfall is closed from January to March, however, you can still access the lake on snowshoes or cross-country skis.
This English-language text was created by the Japan Tourism Agency.
