Ranked in Japan's Top 100 Hot SpringsKawashima Ryokan is located in Toyotomi Onsen, one of the northernmost hot spring resorts in Japan. Known for its petroleum-based spring water, Toyotomi Onsen is one of the most loved in all of Japan, thanks to its benefits for skin health and beauty. Only a few hot springs, such as Tsukioka Onsen and Niitsu Onsen in Niigata, are naturally infused with petroleum. In fact, the hot springs in Toyotomi were discovered in 1926, during a search for oil. The spring water is so dark that bathers can't see the bottom of the bathtub! One of the top 100 hot springs i...