Kazuma Onsen

Kazuma Onsen in Tokyo is one of the rare naturally occurring carbonated thermal springs found within Japan's largest metropolitan area, a geological surprise in a city that sits atop the complex alluvial geology of the Kanto plain, where naturally heated and mineralized groundwater occasionally surfaces in unexpected locations far from the volcanic mountain systems typically associated with Japanese onsen. The spring's carbonated mineral waters produce the characteristic effervescent tingling on the skin associated with dissolved carbon dioxide, the rarest and most prized water type in Japan's onsen classification system, giving this urban Tokyo spring an exceptional quality that contrasts dramatically with its metropolitan surroundings. Kazuma Onsen offers the remarkable experience of bathing in naturally carbonated volcanic water within one of the world's most densely populated cities, connecting urban residents to the geological heritage of the deep earth that lies beneath the built landscape of the Japanese capital.