The Largest Diamond Mine

The mine begun in 1955, the pit is now 525 meters deep and 1.25 kilometers across. This diamond mine is so deep that the surrounding "air zone... is closed for helicopters" after "a few accidents when they were 'sucked in' by downward air flow...".The massive 20-foot tall rock-hauling trucks that service the mine travel along a road that spirals down from the lip of the hole to its basin. Round-trip travel time: two hours. Meanwhile, something completely different and Jules Vernian is about to happen thanks to some Japanese scientists hoping to drill down into the earth's mantle: "Using a giant drill ship launched (in July 2005), the researchers aim to be the first to punch a big hole through the rocky crust that covers our planet and to reach the mantle below." And then, in an oddly Borgesian, or perhaps MC Escherian, moment of nomenclatural mise-en-abîme, "The 57,500-tonne drill ship Chikyu (Japanese for Earth) is being prepared in the southern port of Nagasaki. Two-thirds the length of the Titanic, it is fitted with technology borrowed from the oil industry that will allow it to bore through 7,000 metres of crust below the seabed while floating in 2,500 metres of water – requiring a drill pipe 25 times the height of the Empire State building."

reference : http://bldgblog.blogspot.com and bbc