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.
Belum Caves
The Belum Caves is the largest and longest cave system open to the public on the Indian subcontinent, known for its speleothems, such as stalactite and stalagmite formations. The Belum Caves have long passages, galleries, spacious caverns with fresh water and siphons. This cave system was formed over the course of tens of thousands of years by the constant flow of underground water. The cave system reaches its deepest point ( from entrance level) at the point known as "Pataalaganga". In Telugu language, it is called " Belum Guhalu". Belum Caves have a length of , making them the second largest caves on the Indian Subcontinent after the Krem Liat Prah caves in Meghalaya. It is one of the centrally protected Monuments of National Importance.