6. Darvaza gas crater “Door to Hell”
Crater width: 226 feet (69m)
Depth: 98 feet (30m)
In 1971 Soviet scientists messed up setting up a borehole for gas, and everything collapsed into a newly created sinkhole. To stop the spreading of poisonous gas they set it on fire. More than 40 years later, and the gas in this extraordinary sinkhole in Turkmenistan is still burning. The scientists setting it on fire, supposedly believed that the fire will last for a few weeks. We simply had to include this natures wonderful monument to human greed and ignorance in our list of 10 biggest deepest holes in the world.
