 How about this one from Mirna in Eastern Siberia: the Mirny Diamond Mine: 525 meters deep and 1.25 km in diameter!Air currents, due to convection, are so strong above the mine, that several helicopters have crashed. So at this time, all flights above the hole are being prohibited! |
 Or the Kimberley Big Hole in South Africa: Reportedly the largest hand-dug excavation in the world. 1097 meters--a bit over five-eighths of a mile--deep. |
 The Bingham Canyon Mine southwest of Salt Lake City in Utah. (According to Wikipedia, "As of 2004, ore from the mine has yielded more than 17 million tons (15.4 Mt) of copper, 23 million ounces (715 t) of gold, 190 million ounces (5,900 t) of silver, and 850 million pounds (386 kt) of molybdenum. The gold and silver are impurities removed from the copper during refining. The value of the resources extracted from the Bingham Canyon Mine is greater than the Comstock Lode, Klondike, and California gold rush mining regions combined." |
 And then, finally, this pretty one: the Great Blue Hole in Belize--close to a quarter mile across and 145 meters deep in the center. |
As always: Enjoy!
