For a natural experience of a different kind, make your way to the steaming pools of Mountain Hell Hot Springs. This spot is renowned for its mineral-rich thermal waters.
You'll soon learn why this Beppu naturally heated water source is popular with travelers. If you're looking for more to do and see here, Hells of Beppu, African Safari, and Takegawara Onsen are in the area as well. They won't take you long to reach from Mountain Hell Hot Springs.