Okunikko Yumoto Onsen Yunokoso

Yunokoso is a small ryokan famous for its cloudy sulfur water, standing on the shore of Lake Yunoko at an altitude of about 1,478 meters in Nikko, Tochigi Prefecture. Okunikko Yumoto Onsen is an ancient hot spring said to have been discovered in 788 by the monk Shodo Shonin, the founder of Nikko, and in 1954 it became the first place in Japan designated as a National Health Resort Hot Spring. It lies on the north shore of Lake Yunoko, beyond the Senjogahara marsh, in a quiet spa village often called the inner retreat of Nikko.

The bath is fed by free-flowing sulfur spring water that is colorless when it emerges but turns emerald green and then milky white on contact with air and light. The water is a sulfur-bearing sodium-calcium chloride-sulfate spring (hydrogen sulfide type), with a source temperature of about 62.5C and a pH of around 6.3. The slightly hot water carries a distinct sulfur scent and is said to be effective for nerve pain, rheumatism, joint pain, and fatigue recovery.

With only 16 guest rooms, the inn is intimate, and its large indoor bath offers the cloudy water exactly as it flows from the source, without added water or heating. Overnight stays with two meals start from 11,000 yen (tax and bathing tax extra). Check-in is at 15:00 and check-out at 10:00, and free parking for 10 cars is provided.