Yubara Onsen Sunayu

A free open-air mixed bath (konyoku, 混浴) carved into the riverbed below the Yubara dam, where alkaline simple spring water wells up naturally through the sand and gravel. There are no walls or enclosures, just a large natural pool with the dam face looming above. Women can enter wrapped in a towel or light clothing. The contrast of cold air and hot water in winter is particularly vivid.