https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole
The Kola Superdeep Borehole is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, on the Kola Peninsula. The project attempted to drill as deep as possible into the Earth’s crust. Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. Boreholes were drilled by branching from a central hole. The deepest, SG-3, reached 12,262 metres (40,230 ft) in 1989 and is still the deepest artificial point on Earth. The borehole is 23 centimetres (9 in) in diameter.
In terms of true vertical depth, it is the deepest borehole in the world. For two decades it was also the world’s longest borehole in terms of measured depth along the well bore, until it was surpassed in 2008 by the 12,289-metre-long (40,318 ft) Al Shaheen oil well in Qatar, and in 2011 by the 12,345-metre-long (40,502 ft) Sakhalin-I Odoptu OP-11 Well (offshore from the Russian island of Sakhalin)
WOW!
And then there’s Mel’s Hole @ 80,000+ feet deep before the US Government took over the site:
https://www.youtube.com/watch?v=sA5KIRChve0