Amazing place for a foot bath. The Hell Valley is the centre of explosion of a volcano and as such, it's full of natural hot spas.
There is no admission fee.
Official website http://www.noboribetsu-spa.jp/?see=jigokudani2&lang=en
More information http://www.japan-guide.com/e/e6751.html
Address Japan
Coordinates 42°29'50.867" N 141°8'48.948" E