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.
Belum Caves
The Belum Caves is the largest and longest cave system open to the public on the Indian subcontinent, known for its speleothems, such as stalactite and stalagmite formations. The Belum Caves have long passages, galleries, spacious caverns with fresh water and siphons. This cave system was formed over the course of tens of thousands of years by the constant flow of underground water. The cave system reaches its deepest point ( from entrance level) at the point known as "Pataalaganga". In Telugu language, it is called " Belum Guhalu". Belum Caves have a length of , making them the second largest caves on the Indian Subcontinent after the Krem Liat Prah caves in Meghalaya. It is one of the centrally protected Monuments of National Importance.