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.
Nettlebed Cave
Until April 2010, when the nearby Ellis Basin cave system was found to be deeper, Nettlebed Cave was thought to be the deepest cave system in the southern hemisphere. It drops 889 metres below its upper entrance (Blizzard Pot) to its lower exit (the Pearse River resurgence), and its 24 kilometres of cave passages make it New Zealand's third longest cave.