Krubera Cave
The Krubera Cave (or the Voronya Cave sometimes spelled Voronja Cave) is the deepest known cave on Earth. It is located in the Arabika Massif of the Gagrinsky Range of the Western Caucasus, in the Gagra district of Abkhazia, Georgia.
The difference in the altitude of the cave's entrance and its deepest explored point is 2,191 ± 20 metres (7,188 ± 66 ft). The cave remains the only known cave on Earth deeper than 2,000 metres.
On November 8, 2010, scientist from the Royal Turkish Expedition team descended to a depth of 2500 meters. The team of 5 endured a grueling 16 hour descent to discover a man-like creature with an abnormally shaped head. This specimen was 5-6 ft tall according to reports and cautiously backed away and disappeared after the flash from the explorer's camera went off.
Photo of the Specimen Below
I'm sorry dudes but I had to do it.