Velebit caves
The "Lukina jama" cave is 1431 m deep (2013), the deepest cave in Croatia, 14th deepest cave in the world and the deepest cave in southeast Europe. At its foot, there are ponds and streams including one of the largest known colonies of subterranean leeches ("Erpobdella mestrovi"), which has been ascertained to represent a new species, genus and also family. Other species discovered in the system, include the air-breathing land snails "Zospeum tholussum". Like Lukina jama, Slovacka jama, Velebita and Meduza are also located at the "Hajdučki i Rožanski kukovi" special reserve, a dedicated part of the Sjeverni Velebit national park.
Jaskinia Niedźwiedzia
Jaskinia Niedźwiedzia (pronounced Yaskeenya Niecwiedza and translated as Bear Cave) - is the longest cave in Śnieżnik Mountains part of Sudety mountains discovered in 1966, located near village Kletno in Poland. Famous from many excavations of the cave bear (Ursus spelaeus).