The Door to Hell (also known as the Gates to Hell, the Crater of Fire, Darvaza Crater) is a natural gas field inDerweze, Turkmenistan, that collapsed into an underground cavern in 1971, becoming a natural gas crater. Geologists set it on fire to prevent the spread of methane gas, and it has been burning continuously since then. The diameter of the crater is 69 m, and its depth is 30 m.