What criteria are you using for that? I argue any excavation counts as a hole so my first instinct is that surely the Africans hold the title with their crazy mines. They go very deep looking for gold (& diamonds from what I recall).
I doubt the borehole in the original article goes straight down. Boreholes tend to list left and right.
I doubt the borehole in the original article goes straight down. Boreholes tend to list left and right.
https://en.wikipedia.org/wiki/List_of_deepest_mines