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.
Oudomxay Province
Chom Ong Cave, the longest cave in Laos, is located in Ban Chom Ong, 45 km to the northwest of Oudomxay town and is the biggest known cave in northern Laos. The cave was explored by a team of cave researchers during 2009, 2010 and 2011 and reported to be 18.4 km long and considered as the second longest in Laos and 9th longest in South East Asia. The average dimensions of the cave is 20–25 m in width and 20–30 m in height. It has two passages, one is a stream and the other has fossils and both connect to a large hall which is 100 m long, 30 m wide and of varying height of 30–50 m up to the roof. It has a stream inlet in the north and the stream outflows in the southern end.