The Door to Hell is a natural gas field in Derweze. The Door to Hell is noted for its natural gas fire which has been burning continuously since it was lit in 1971. The fire is fed by the rich natural gas deposits in the area. The pungent smell of burning sulfur can be noticed in the area for some distance. The crater is 230 feet wide and is referred to as the Door to Hell by locals because of endless flames and boiling mud that can be found inside. Originally a level surface, the site was found by Soviet scientists in 1971 as an area that was believed to house a substantial oil field. A camp and drilling rig were set up nearby, and, after the Soviets were pleased with amount of gas resources that were believed to be at the site, it was agreed that gas from the field would start being stored. However, the ground beneath the drilling rig soon collapsed, creating a wide crater that was believed to be releasing large quantities of methane gas, a potential danger to the nearby villages. Scientists decided that the most efficient way to solve the problem would be to burn off the poisonous gases – by doing so, it was expected that all of the gas in the crater would be burnt off within a few days. But more than four decades later the crater is still ablaze and hundreds of tourists flock to visit it every year.