Krubera Cave
The difference in elevation of the cave's entrance and its deepest explored point is . It became the deepest-known cave in the world in 2001 when the expedition of the Ukrainian Speleological Association reached a depth of which exceeded the depth of the previous deepest-known cave, Lamprechtsofen, in the Austrian Alps, by . In 2004, for the first time in the history of speleology, the Ukrainian Speleological Association expedition reached a depth greater than , and explored the cave to . Ukrainian diver Gennadiy Samokhin extended the cave by diving in the terminal sump to 46 metres' depth in 2007 and then to 52 m in 2012, setting successive world records of 2,191 m and 2,197 m, respectively. Krubera is one of the two known caves on Earth deeper than 2,000 metres.
Tears of the Turtle Cave
The entrance to Tears of the Turtle Cave was found in 2006. The cave passage is mostly a two to three foot wide fissure that follows a stream downward through numerous rappels. In 2014 a team of nine cavers explored new passage pushing the cave to a depth of 1629 feet and in doing so passed New Mexico's Lechuguilla Cave to become the deepest known limestone cave in the United States. Exploration continued in 2016 when teams returned to push the cave to its current known depth of 1659 feet. On those trips the difficulty necessitated establishing camp in the cave for the first time. This, along with the technical rope work, 39 degree temperature, and remote location of the cave make continued exploration difficult. A return trip is currently planned for 2019.