The Kola Superdeep Borehole is the deepest hole in the world. How deep is it?

Why not fill it back in since the whole idea was pointless and a waste of time?

me, the question is still why? what good will it be for ordinary plebs like me?

The project attempted to drill as deeply as possible into the Earth's crust. The stated areas of study were the deep structure of the Baltic Shield, seismic discontinuities and the thermal regime in the Earth's crust, the physical and chemical composition of the deep crust and the transition from upper to lower crust, lithospheric geophysics, and to create and develop technologies for deep geophysical study. Another unexpected discovery was a large quantity of hydrogen gas. The drilling mud that flowed out of the hole was described as "boiling" with hydrogen.[13] In 1992, an international geophysical experiment obtained a reflection seismic crustal cross-section through the well. The Kola-92 working group consisted of researchers from the universities of Glasgow and Edinburgh in Scotland, the University of Wyoming in the United States, and the University of Bergen in Norway, as well as several Russian earth science research institutions.[14] The experiment was documented in a video recorded by Professor David Smythe,[15] which shows the drilling deck in action during an attempt to recover a tool dropped down the hole.

M198Gonzo, It's too deep to fill it back in and I don't think it is possible since it would probably not return to its original shape even if you out it back in

Nearlyfit, To find out the centre of the Earth or something to do with Sciences

PinkDoorZepln, but it's only 9 inches(.22 meters) in diameter ~ lol!

me, good answer

me, just imagine if everyone start digging for sake of geo studies?