Mir Mine is a former open pit diamond mine located in Mirny, Eastern Siberia, Russia.
At the time of its closing in 2004, the mine was 525 meters deep and 1,200 meters across making it the second largest excavated hole in the world, after Bingham Canyon Mine. The hole is so big that airspace above the mine is closed for helicopters because of incidents in which they were sucked in by the downward air flow.
During the brief summer months, permafrost would become mud turning the entire mining operation into a land of sludge. Buildings had to be raised on piles, so that they would not sink. The winter temperatures were so low that car tires and steel would shatter and oil would freeze.
During the winter, workers used jet engines to burn through the layer of permafrost or blasted it with dynamite to get access to the underlying kimberlite. The entire mine had to be covered at night to prevent the machinery from freezing.