Kirishima Onsen Kawanoyu is a free wild hot spring (noyu) located along the Maruo Nature Trail in Makizono-cho Takachiho, Kirishima City, Kagoshima Prefecture. Known as the most accessible wild hot spring, visitors can even stroll from the hot spring town in yukata robes, making it suitable for beginners of all ages. As the name suggests, the entire river is a natural hot spring where you can bathe anywhere you like. The characteristic thick milky white sulfur spring water makes it relatively comfortable for women as visibility in the water is limited. Bathing with bath towels or swimsuits is acceptable. Water temperature varies by location - typically the area near the bridge by Menoyu is lukewarm and suitable for summer, with temperatures increasing upstream. In spring and autumn, the ideal spot is several dozen meters upstream from the bridge, and even further upstream in winter. After rain, water volume increases and temperature drops, moving the comfortable bathing spot further upstream. The river is narrow with depths of only a few dozen centimeters, making it safe. Adjacent to Kawanoyu is Menoyu, the oldest rock bath in Kirishima. There are no changing rooms or facilities, so bathing is at your own risk.