> even more massive Kola Superdeep Borehole? Kola Superdeep Borehole is not massive. It's a small cylindrical hole in the ground: https://en.wikipedia.org/wiki

> even more massive Kola Superdeep Borehole? Kola Superdeep Borehole is not massive. It's a small cylindrical hole in the ground: https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#/media/File:%D0%A1%D0%B0%D0%BC%D0%B0_%D1%81%D0%BA%D0%B2%D0%B0%D0%B6%D0%B8%D0%BD%D0%B0(%D0%B7%D0%B0%D0%B2%D0%B0%D1%80%D0%B5%D0%BD%D0%B0),_%D0%B0%D0%B2%D0%B3%D1%83%D1%81%D1%82_2012.JPG https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole#/media... Mponeng is a massive continuously commercially operating mine with 5k workers