The Fire Falls of Krypton
The Fire Falls are made up of spectacular ribbons of fire from the core of Krypton itself that spill over tall scenic rock formations (S No. 141, Nov 1960: "Superman"s Return to Krypton!" pts. I-III—"Superman Meets Jor-El and Lara Again!"; "Superman's Kryptonian Romance!"; "The Surprise of Fate!"). While differing from waterfalls, the Fire Falls do contain Fish-Snakes--eel-like creatures with a poisonous bite.
A magnificent flaming cataract on the planet Krypton formed by a "fiery fluid" pouring over a precipice (Act No. 325/1, Jun 1965: "The Skyscraper Superman!"). Jor-El describes the spectacular phenomenon as "[o]ur planet's inner fires, pouring through a fissure" in a massive rock cliff (S No. 141, Nov 1960: "Superman"s Return to Krypton!" pts. I-III—"Superman Meets Jor-El and Lara Again!"; "Superman's Kryptonian Romance!"; "The Surprise of Fate!").
Various species of "mutant fish" inhabit the Fire Falls, including venomous "fish-snakes" whose bite is potentially fatal (Act No. 281/1, Oct 1961: "The Man Who Saved Kal-El's Life!"). According to Action Comics No. 324/2, "When the planet [Krypton] exploded, it hurled the falls into space, where the flames turned into a kind of kryptonite, like all other parts of Krypton," so that today, on a far-off asteroid somewhere in outer space, the famed Fire Falls still exist, in the form of a stunning green cataract of "kryptonite flame" (May 1965: "The Black Magic of Supergirl!"). (TGSB)