The hot springs here have the highest temperature of any springs in the Datunshan volcano group. The dreamlike misty scenery here made it one of the “12 great sights of Taiwan” during the Japanese era.
The temperature of the hot spring water in Thermal Valley is between 60 to 70℃, and the hot springs are classified as acid sulfate/chloride springs. They are commonly called "Green sulfur springs," but although the water is corrosive, it has a very low Ph.
Furthermore, a mineral from Thermal Valley called “Beitou Stone” or "Hokutolite" is the only one of the thousands of minerals from around the world to be named after a place in Taiwan. It was discovered in 1905 by a Japanese man named Okamoto Yohachiro, who found that the mineral contains the radioactive element radium. At present, only Beitou in Taiwan and Tamagawa Hot Spring in Akita Prefecture, Japan possess this kind of mineral.
In order to restore Hokutolite, a Hokutolite nature reserve has been set up in recent years. Visitors not only can enjoy the hot springs, but can also get a deeper understanding of this unique mineral.