The deepest hole we've dug is probably the Mir diamond mine in Siberia, at 525m [0]
(A quick internet search will probably say that the Bingham copper mine in the US is deeper, but that was dug at the bottom of an existing canyon, giving it a head start; the Mir mine started... Well, basically with a bunch of guys with shovels in the middle of the tundra.
The deepest hole we've dug is probably the Mir diamond mine in Siberia, at 525m [0]
(A quick internet search will probably say that the Bingham copper mine in the US is deeper, but that was dug at the bottom of an existing canyon, giving it a head start; the Mir mine started... Well, basically with a bunch of guys with shovels in the middle of the tundra.
[0] https://www.atlasobscura.com/places/mir-diamond-mine