Tamagawa Onsen

Tamagawa Onsen has the highest flow rate of any hot spring in Japan, at 9,000 liters per minute, and its pH of 1.2 makes it the most acidic. The spring was discovered in 1681 and has drawn visitors seeking therapeutic bathing since it opened formally in the 1880s. A 30-minute nature research path winds past the Obuki spring, where water surfaces at 98 degrees Celsius and steam rises from vents in the ground. Along the path, rocks heated by geothermal energy become natural stone saunas where visitors lie on mats, warming their muscles from the heat radiating up from below.