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.
Quri Qala Cave
Quri Qale Cave or QuraQala (Kurdish: Şkefta QureQela, ئەشکەوتی قوڕەقەڵا Persian: غار قوری قلعه) is a cave located northwest of Ravansar, Iran, and is one of the longest caves in western Asia. First explored in the 1950s, in 1989 it was further opened by an Iranian team. It contains three main chambers, with calcite crystals, stalactites and waterfalls. It is known for its colony of mouse ear bats, and for a number of archaeological finds, including silver plates dating the late Sassanian period.