The second largest manmade hole in the world (surpassed only by the Bingham Copper Mine in Utah) is a diamond mine located on the outskirts of Mirny, a small town in eastern Siberia.
Excavation on the pit began in 1955, and today it is 1,722 feet (525 meters) deep, and 3,900 feet (1.25 kilometers) across. Stalin ordered construction of the mine to satisfy the Soviet Union’s need for industrial-grade diamonds following the war.
The harsh, frozen Siberian landscape made working on the mine a difficult proposition at best. Jet engines were turned on the unyielding permafrost in order to melt it; when that failed, explosives were used. During its peak years of operation, the Mirny mine produced over 10 million carats of diamonds annually, a good percentage of which were gem-quality.
The upper layers of the mine had very high diamond content of 4 carats per tonne of ore, with the relatively high ratio of gems to industrial stones. The largest diamond of the mine was found on 23 December 1980; it weighed 342.5 carats.
Operations ceased in 2001, but the site didn’t lie dormant for long. Diamond mining now takes place in great volumes at the Mir Underground Mine, which lies just underneath the original open pit. To get to the base of the pit, massive 20-foot tall rock-hauling trucks travel along a road that spirals down from the lip of the hole to its basin. The round-trip travel time is two hours.
Though it has been said that the airspace above the mine is off-limits to helicopters, after “a few accidents when they were ‘sucked in’ by downward air flow,” there is no evidence to substantiate the claim.