The oldest hot spring in Japan with a history of about 1,800 years, Yunomine Onsen has long been known as a place of purification and rest for travelers on pilgrimages to Kumano.
It was discovered around the 4th century, and later made its name known throughout Japan through the Kumano pilgrimages of successive emperors.
The hot spring resort town, with its therapeutic hot spring atmosphere, is lined with inns along the Yunotani River, a tributary of the Kumano River, and is surrounded by a cedar forest, making it a quiet valley hot spring.
The hot spring water is distributed in more than a dozen places around the riverbed of the Yunomine River, and bubbles accompanying the export of hot spring water from the riverbed can be observed.
The spring is classified as a sulfur-containing bicarbonate spring with chloride, bicarbonate, and sodium as its main components.
The gush temperature is 92.5°C, and the overall gush rate of Yunomine Hot Spring is 885 liters/minute. The spring is said to be effective for neuralgia, rheumatic diseases, skin diseases, and diabetes.
Along the river, there is a “yuzutsu,” a self-heating hot spring water outlet, from which local people boil hot spring eggs, vegetables, and wild plants, and tourists can also boil eggs and vegetables.
There is a public bathhouse in the center of the hot spring resort, and a “tsuboyu,” a natural hot spring rock bath at the foot of the creek bridge.
Tsuboyu was registered as part of the UNESCO World Heritage Site “Sacred Sites and Pilgrimage Routes in the Kii Mountain Range” as a place for Kumano pilgrims to purify themselves.
It is the only World Heritage site in the world where visitors can bathe in hot spring water.
Inside a hut-like building on the bank of the Yunotani River is a small bathtub made of natural stone.
The bathtub is cozy and large enough for two adults.
The color of the water is sometimes clear, sometimes milky white, and sometimes bluish, and there is a legend that the color of the water changes seven times a day.
The public bathhouse has two types of hot spring baths: a “general bath” where the temperature is adjusted by adding water due to the high temperature of the source, and a “kusuri-yu” where the water is cooled and not added to the source.
The public bathhouse also has a hot spring water pump where visitors can take hot spring water home with them.