The Door to Hell (also known as the Gates to Hell, the Crater of Fire, Darvaza Crater) is a natural gas field in Derweze,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 69m,and its depth is 30m.The crater is a popular tourist attraction.In the past five years 50,000 tourists have visited the site.The gas crater has a total area of 5,350m the size of an American football field.The surrounding area is also popular for wild desert camping.