Caves Facts

The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!

Mammoth Cave in Kentucky is the longest cave system on Earth - over 400 miles of tunnels. In 1842, Dr. John Croghan moved 16 sick patients underground, convinced that cave air would cure their illness. At least five died inside. Nearly all the others died within weeks of leaving. The doctor died of the same disease in 1849.

Miners in Mexico found a hidden cave in 2000 with the largest crystals on Earth. The crystals were white gypsum beams up to 37 feet long and 3 feet wide. The heat inside hit 136 degrees with near-total humidity. Without a cooling suit, a person can die within about 10 minutes. In 2015, the mine flooded and sealed the cave shut.

Lee Berger found 1,550 fossils of an unknown human species in South Africa's Rising Star cave. The only way in was an 18-cm gap. He couldn't fit. He posted on Facebook for scientists slim enough to squeeze through. Six women answered. They crawled in and pulled out Homo naledi - a lost branch of humanity. Eight years later, Berger lost 25 kg and finally made it in himself.