Krubera Cave

Krubera Cave (or Voronya Cave, sometimes spelled Voronja Cave) is the deepest known cave on Earth. It is located in the Arabika Massif of the Gagra Range in  Abkhazia, a breakaway region of Georgia.

The difference in elevation of the cave's entrance and its deepest explored point is 2,197±20 meters. It became the deepest-known cave in the world in 2001 CE when the expedition of the Ukrainian Speleological Association reached a depth of 1,710m which exceeded the depth of the previous deepest known cave, Lamprechtsofen, in the Austrian Alps, by 80m. In 2004, CE for the first time in the history of speleology, the Ukrainian Speleological Association expedition reached a depth greater than 2,000m, and explored the cave to −2,080m. Ukrainian diver Gennadiy Samokhin extended the cave by diving in the terminal sump to 46m depth in 2007 CE and then to 52 m in 2012 CE, setting successive world records of 2,191m and 2,197m respectively. Krubera remains the only known cave on Earth deeper than 2,000 meters.

Krubera was chosen to create a hermetically sealed and hidden chamber where 2,500 humans would sleep in suspended animation as part of Operation Deep Sleep until the Xunx would suspend their activities again and emerge either to repopulate Earth or to join Humanity after successfully beating the Xunx. They were forgotten until Stahl asked McElligot about them in 4300 OTT. They were successfully revived at that time.