This is the worlds biggest open cast diamond mine in Mirny, north eastern Siberia. It’s more than 1 km in diameter and half a km deep! Wow, that’s a big hole. The Google Maps imagery isn’t super high-res but there are some good photos about. Thanks: Mihaly Homonnai, alvus, Adam Hauner, targon, Yuri, Dustin, sz, Troels, Peter Berenyi, Marcin & Josh Brandt.