Kusatsu Yubatake Rotenburo

Kusatsu Yubatake Rotenburo in Kusatsu, Gunma Prefecture, offers open-air bathing within view of the famous Yubatake, or Hot Water Field, a central feature of Kusatsu Onsen where volcanic spring water flows through a network of wooden channels in a display of geothermal abundance that makes Kusatsu one of the most visually dramatic onsen towns in Japan. The siliceous and highly acidic spring water of Kusatsu, with a pH as low as 2, has a well-documented bactericidal effect that made these springs historically celebrated across centuries of Japanese bathing tradition — earning the town a proverbial reputation that only heartache lay beyond the waters' reach. The town's unique yumomi tradition, in which long wooden paddles are used to cool the spring water to bathing temperature, performed to traditional folk songs, preserves an intangible cultural heritage at the heart of Kusatsu's distinctive onsen identity.