
Years back (1971 to be precise), Soviet geologists started drilling a site near to Derweze, Turkmenistan, thinking that it had huge reserves of oil. However, they soon realized that they were working on top of a giant gas crater, which collapsed shortly after work began (surprisingly no one was killed). Although some dispute the origin of the crater, many believe that its because of this Soviet expedition to explore for gas.
Soon, there was widespread fear that the gases emitting from the crater were poisonous. Geologists set it on fire in 1971 to prevent the spread of methane gas (they thought the fire would die down in a weeks time). However, surprisingly, it has been burning continuously since then.
Take a look at this video to understand the science behind this phenomenon.
Over the years, the crater has turned is a popular tourist attraction, with several visitors turning up every year to see the site. The gas crater is around the size of an American football field. The surrounding area is also popular for wild desert camping.
The Door to Hell (also known as the Gate to Hell, the Crater of Fire, Darvaza Crater) is a natural gas field in Derweze, located in Ahal Province in Turkmenistan.

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