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.
Cades Cove
The fracturing and weathering of the limestone and sandstone in Cades Cove has led to the formation of several caves in the vicinity, the two largest of which are Gregory's Cave and Bull Cave. Bull Cave, at 924 feet (281 m), is the deepest cave in Tennessee. Trilobite and brachiopod fossils have been found in Gregory's Cave.