In 1980 an oil drilling rig accidently drilled into the roof of an active salt mine, at a point underneath a lake. Watch this video of it. It's an interesting display of the power of natural forces
Lake Peigneur sinkhole disaster
The next picture is a large crater that is a result of a Soviet gas exploration accident in the 1950’s. It was created when a Soviet drilling rig was drilling for natural gas fell into an underground cavern resulting in a crater which today measures roughly 60 meters in diameter and 20 meters deep. The huge crater was set alight shortly after being discovered and has been burning ever since. The smell of burning sulfur can be detected from a distance and becomes quite strong as you near the hot edge of the crater.
The Door to Hell – Burning Gas Crater in Darvaza, Turkmenistan
