The Thermal Valley () is a valley located on the foothill of Yangmingshan National Park in Beitou District, Taipei, Taiwan. This makes Thermal Valley one of the sources of acidic sulfur hot spring in the area. Locals also sometimes refer to it as Hell Valley. The formula of this mineral water contains Plaster, Alunite, Jarosite, Realgar, Sulfur, and Radium. pH value is between 1.4~1.6, the highest temperature could be reached to 90 Celsius. It was one of the eight attractions and twelve scenic spots in Taiwan during the Japanese colonial period.