The Darvaza Gas Crater is a hole about 70 metres across in the Karakum desert of central Turkmenistan that has been on fire for more than fifty years, since Soviet drillers set alight the natural gas leaking from it, and it burns with no fence around the rim and nothing for kilometres in any direction. The story most often told is that a drilling rig in 1971 broke through into a gas pocket, the ground collapsed, and geologists lit the escaping gas expecting it to burn off in weeks; it is still burning, and the details of the date and the decision have never been documented. Locals call it the Door to Hell. After dark the crater fills with orange light, scattered pockets of flame now rather than the unbroken ring that burned here for decades, still visible far across the black desert, with heat rolling off the pit onto the faces at the rim.
By day the drama fades and the crater shows its bones: a broad circle of blackened, crumbling rock with pale flames flickering low among the stones and heat haze rising off it, in a flat desert of sand and scrub with camels passing. The pit has been entered once. In 2013 the Canadian explorer George Kourounis descended to the floor in a heat-reflective suit and found bacteria living in the hot soil that were absent from the desert around it. Two quieter siblings lie nearby, left by the same ground collapse: a water-filled crater bubbling with gas about 23 kilometres away, and a mud crater roughly ten kilometres off. Most people arrive from Ashgabat by 4x4 across the desert and pitch a tent on the cooling sand a short walk from the crater, staying on after the day visitors leave to watch the glow under a sky with no light in it but stars. Turkmenistan's government has talked more than once of putting the fire out, and so far the desert has kept its door open.