Darvaza gas crater

The Darvaza gas crater, also known as the Door to Hell or Gates of Hell, is a natural gas field collapsed into a cavern near Darvaza, Turkmenistan.Accurate records of how the crater ignited have not been discovered, and some facts are disputed. One of the more popular theories is that Soviet geologists intentionally set it on fire in 1971 to prevent the spread of methane gas, and it is thought to have been burning continuously ever since. The gas crater has an area of 5,350 m2. Its diameter is 69 m, and its depth is 30 m.The Turkmen government hopes that the crater will become a popular tourist attraction. The surrounding area is also popular for wild desert camping.

Source: Wikipedia