This diamond mine in eastern Siberia (Mirny, to be exact) 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..."

Finally, look for the tiny red arrow in the following photograph; it's pointing to a 220-ton rock-hauling truck more than 20' tall.

Meanwhile, something altogether different and Jules Vernian is about to occur 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 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."
      For some sense of perspective here, the diamond mine, pictured above, is 1200 meters deep; that means that to reach the mantle, the Japanese will have to produce a drill-hole nearly seven times deeper than the mine (which sounds alarmingly easy, actually – I was expecting to be horrified).
      In any case, the drill-ship is called *Earth* and it's being drilled down into the earth... The attack of the simulacra begins.