The Fire Falls were a chain of lava falls located on Krypton. For some reason, magma welled up through a fissure and streamed down a cliff.
In Earth-One, the Fire Falls were located near Argo City and the Scarlet Jungle. The Falls are home to various dangerous species like the venomous Fish-Snakes. During the wars against the Vrangs, Hatu-El and his rebel followers took shelter in the Falls. Somehow, that piece of Krypton wasn't damaged when the planet exploded. Many years later, when the Kandorians settled in Rokyn, they recreated the Fire Falls near the enlarged Kandor.
In New Earth, Kryptonian legends maintained that the Falls were created when Rao cried tears of flame for one hundred nights after being tricked into imprisoning Cythonna, although some scientists attributed the phenomenon to fluids secreted by Blood Bloom plants growing on the Falls' rocky walls. Various species of giant birds of prey inhabited the area.