Mount Roraima Venezuela, Brazil and Guyana Mount Roraima is a pretty remarkable place. It is a tabletop mountain with sheer high cliffs on all sides. There is only one ‘easy’ way up, on a natural staircase-like ramp on the Venezuelan side
The Derweze area is rich in natural gas. While drilling in Soviet geologists tapped into a cavern filled with natural gas. The ground beneath the drilling rig collapsed, leaving a large hole. Locals have dubbed the cavern "The Door to Hell".
Hells Door It is situated near the small town of Darvaz in Turkmenistan. A few years ago, geologists were drilling for gas when then encountered a very large cavern underground filled with a poisonous gas.