4The Mponeng Gold Mine (4,000 meters)

South Africaโ€™s Mponeng Gold Mine is the deepest mine in the world, stretching more than 4 kilometers below the surface.

Miners endure extreme heat and pressure to extract gold. Temperatures in the mine can reach up to 60ยฐC (140ยฐF), making it one of the most challenging workplaces on Earth.