The Mir mine, also called the Mirny mine, is an open pit diamond mine located in Mirny, Sakha Republic, in the Siberian region of eastern Russia. It was the Soviet Union's first developed diamond mine, and became its largest after open-pit mining began in 1957. The pit is more than 525 meters deep, has a diameter of 1,200 m, and is one of the largest excavated holes in the world.