Free-flow from source
Tenzan Onsen
A sodium-chloride spring and simple hot spring that wells up from underground. With its devotion to 100% natural free-flowing spring water, not a drop of added water is used, allowing guests to fully enjoy the fresh water. It also includes a highly alkaline spring with a pH above 9.3, which is excellent for smoothing the skin. In the rustic open-air bath overlooking the stream of the Sugen River, you can enjoy Hakone's famous hot spring to your heart's content.