The Darvaza Crater, more commonly known as the Door to Hell, still burns today, a surreal feature in an otherwise barren landscape.
Details on the origin of the sinkhole are sketchy, but the story goes that Soviet scientists set it on fire to burn off noxious gases after the ground under a drilling rig gave way. Perhaps the scientists underestimated the amount of fuel that lay below—Turkmenistan has the sixth largest natural gas reserves in the world.
In November 2013, explorer and storm chaser George Kourounis, on an expedition funded partly by National Geographic, set out to be the first person to plumb the depths of the crater, which is 225 feet (69 meters) wide and 99 feet (30 meters) deep. (Related: "Diver 'Vanishes' in Portal to Maya Underworld.").