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.
Dent de Crolles
The réseau de la Dent de Crolles, which lies beneath the summit plateau, is one of the most complex and longest cave systems in Europe, and is considered to be one of the birth places of modern caving. Its first detailed exploration was during World War II by a small team of French cavers which included Pierre Chevalier, Fernand Petzl, and Charles Petit-Didier. Their explorations saw it become the deepest cave in the world at the time with a depth of . The lack of available equipment during the war forced Pierre Chevalier and the rest of the team to develop their own equipment, leading to technical innovation. The first use of the single rope technique with prusik and mechanical rope-ascenders (Henri Brenot's "monkeys", first used by Chevalier and Brenot in a cave in 1934) can be directly associated with its exploration.