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.
Tears of the Turtle Cave
Tears of the Turtle Cave is located in the Bob Marshall Wilderness in western Montana and is currently the deepest limestone cave in the United States since passing New Mexico's Lechuguilla cave in 2014. As of August 2016 the cave is known to be 1659 feet deep and 1.32 miles long. The cave consists mostly of roughly 2 foot wide fissure passage passing over dozens of short rope drops. With a mean temperature of 39 degrees F (4 C), it is muddy and poorly decorated.