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.
Chevé Cave
In 2004, an international caving expedition led by the U.S. Deep Caving Team discovered a new cave they named J2. The entrance of J2 located 5 kilometers northeast of the Chevé Cave entrance. J2 appears to head in the direction of Chevé Cave, with a predicted intersection beyond the tunnel collapse that stopped the team in 2003. Current expeditions are underway to find a connection between J2 and Chevé Cave, which will produce a cave system more than 2 kilometers in depth. The integration of the entire system will produce a 2,597 meter deep cave and would represent the deepest cave in the world.