The crater, commonly called the "Gates of Hell," has been burning in the Karakum Desert near Derweze, Turkmenistan for more than four decades. (Xinhua Photo)

The crater, commonly called the "Gates of Hell," has been burning in the Karakum Desert near Derweze, Turkmenistan for more than four decades. (Xinhua Photo)

The crater, commonly called the "Gates of Hell," has been burning in the Karakum Desert near Derweze, Turkmenistan for more than four decades. (Xinhua Photo)

The crater, commonly called the "Gates of Hell," has been burning in the Karakum Desert near Derweze, Turkmenistan for more than four decades. (Xinhua Photo)