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.
Ellison's Cave
Ellison's features a number of underground vertical pitches including the two deepest pits in the continental United States: Fantastic (586 feet) and Incredible (440 feet). These two pits lie on opposite sides of the cave. Nearby and parallel to Fantastic are Smokey I (500 feet), Smokey II (262 feet), and other extremely deep pitches. There are over 7 routes to reach the bottom level of the cave from the Fantastic side. Fantastic and Smokey I both extend to TAG Hall, a passage at the bottom of the cave. To reach Fantastic, or the large pits on the Fantastic side, cavers must also descend the Warm Up pit (125 feet).