The deepest hole ever drilled barely scratched the Earth's crust

Starting in 1970, Soviet scientists drilled the Kola Superdeep Borehole in northern Russia, eventually reaching 12,262 metres deep by 1989, the deepest artificial point on Earth. At that depth, rock temperatures of 180°C made further drilling impossible, and the hole still hadn't pierced the crust, which runs tens of kilometres thick.

— Wikipedia contributors, Kola Superdeep Borehole — Soviet Union, drilled 1970-1989