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.
Ghar Parau
A British led caving expedition to the Zagros Mountains in 1971 led to the discovery of the cave. The cave was explored to a depth of 742 m by the time the expedition was forced to return to the surface. The explorers believed that the cave might go on much further, possibly surpassing the Gouffre de la Pierre-Saint-Martin system, which at that time was the world's deepest known cave.