The Darvaza gas crater, also known as the Door to Hell or Gates of Hell, is a natural gas field collapsed into a cavern located in Derweze, Turkmenistan. Geologists intentionally set it on fire to prevent the spread of methane gas and it is thought to have been burning continuously since 1971. This is significant because geologists intentionally set it on fire to prevent the spread of methane gas but it has continuously burned for since.