Deep in the Arctic Circle, there’s a man-made hole that once earned the nickname “the entrance to hell.” The Kola Superdeep Borehole, the deepest hole ever drilled on Earth, reached a staggering 12 ...

Deep in the Arctic Circle, in Russia, lies the deepest hole ever dug which was once called 'the entrance to hell'. The Kola Superdeep Borehole is the deepest manmade hole, and deepest artificial point ...