The second largest man-made hole in the ground is located in Russia. This large pit is actually a diamond mine, which has been inoperable for nearly 10 years.
The pit measures 1722 ft (525 m) in depth and 3936 ft (1200 m) in width. Ironically, the name of the mine is Mir (Russian for "world"). It functioned until the end of 2004, when it was permanently closed.
The Mir mine reached its impressive size after numerous decades of exploitation. For years on end, hundreds of workers dug through the hard earth under inhuman climatic conditions.
The mine is located near the town of Mirny, in the territory of eastern Siberia. At this geographical location, the average winter season lasts for 7 months, and summers are short and rather cool.
In order to obtain a 1 carat diamond, about 550 000 lbs (250 tons) of earth mass must be dug out - that's 550 000 lbs of hard and rigid cold Siberian earth, rock and copper. The use of controlled demolition was a common practice.
Annually, 10, 000, 000 carats of diamonds were mined at Mir.
The large scale quarry creates problems for aerial transport even today, 10 years after its closure.
During the Cold War years, the airspace above the mine was off-limits for fly-by airplanes and helicopters because of the secrecy surrounding it and its purpose.
Years later, with the mine officially closed, it turns out that flying over it can be quite dangerous.
Because of its large size and characteristics funnel shape, helicopters that fly over it create a specific turbulence in the air.
The air masses swirl like a giant funnel and the descending air currents literally "suck in" passing helicopters.
A few flying machines have already become the victims of the strong air currents. For this reason, the airspace above the mine, that looks like a giant hole in the ground from a bird's eye view, is strictly off-limits.
