The eternal fire burns forever in the waterfall in America.
There are thousands of eternal flames in the world but most of them exist because of natural gas in the ground. Most famous are the flames at the "hell hole" in the Karakum desert, Tukmenia has been burning for 40 years due to the natural gas field in the ground.
But the natural eternal fire in New York is different, it does not have any conditions to generate fire. According to scientists, the rocks beneath the fire are not shale type, rocks deep underground, very hot and can maintain gas. Moreover, natural gas cannot penetrate them to "nourish" the fire.
So far, the origin as well as why New York's eternal fire can sustain fire despite harsh weather is still the natural mystery of humanity.