6. Derweze, Turkmenistan
This giant desert crater in Central Asia's Karakum Desert has been on
fire for decades, resembling a scene from a sci-fi movie. Known by
locals as the Door to Hell, it was created when the Russians drilled
here for natural gas, causing the earth to collapse, gas to be released
and fires to rage. Geologists believed that the fires would quickly go
out — but that was back in 1971. The crater, now quite a tourist
attraction, is 160 miles south of the capital, Ashgabat. Most visitors
use the nearby village of Derweze as their base.