Yubara Onsen Sunayu

Yubara Onsen Sunayu is a unique natural hot spring located in Maniwa City, Okayama Prefecture, nestled along the Asahi River. This open-air bathing facility sits directly in the riverbed, where hot spring water naturally bubbles up through the sand and mixes with the cool river water, creating a one-of-a-kind bathing experience. The name "Sunayu" literally translates to "sand bath," referring to the distinctive sandy bottom where bathers can dig to adjust the water temperature to their preference.

The hot spring has a history spanning over 800 years and is known for its therapeutic alkaline waters with a pH of approximately 9.0, which are said to benefit skin conditions and promote overall relaxation. The spring became particularly famous after the construction of the Yubara Dam in 1955, which partially submerged the original hot spring town. The current Sunayu facility was reconstructed downstream and has become an iconic symbol of the region's onsen culture.

Visitors experience the unusual sensation of bathing in an open-air riverside setting where the water temperature varies depending on location and depth. Bathers can dig into the sandy riverbed to find their ideal temperature, as the hot spring water emerges at around 50 degrees Celsius before blending with the cooler river water. The bathing area is mixed-gender and requires swimwear, making it accessible for families and groups. The facility operates year-round, though river conditions may occasionally affect access during periods of heavy rainfall or flooding.

Yubara Onsen Sunayu is located approximately 50 kilometers north of Okayama City. Visitors can reach the area by taking the JR Hakubi Line to Chugoku-Katsuyama Station, followed by a 25-minute bus ride on the Maniwa Kotsu bus bound for Yubara Onsen. By car, the journey from Okayama takes roughly 90 minutes via Route 313.