Nicknamed 'The Door to Hell', the fires in this crater have been burning for over 40 years. To prevent the gas from seeping out, the geologists decided to set fire to it in 1971 near the small village of Derweze in Turkmenistan . They anticipated the gas would burn off over the next few days but some 40 years later, the flames are still burning.The unceasing inferno can be seen for miles and has become a tourist attraction, but it came into being by mistake.

The area, located in Turkmenistan's Karakum Desert, is rich in natural gas and geologists came here in 1971 to drill for it. What they didn't know was that they were drilling above an enormous underground cavern, which collapsed as they bored into it, leaving behind a 70m-wide crater.

  It's difficult to estimate how much gas was in this crater, or how much might still be left. However, the President of Turkmenistan visited the crater this year and decided it might need to be closed to prevent it affecting other natural gas supplies nearby.

The Darvaza well is not a work of nature, but the result of an unfortunate soviet mining prospection started in the 50's. In 1971, a drilling provoked the collapse of an underground cavity, so revealing a gaping hole leaking enormous quantities of gas.

The intense heat coming from the crater allows to approach the place only for a few minutes because of the unbearable temperature.

BBC Focus Magazine