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.
Castellana Caves
The Caves of Castellana open in south-eastern Murge, a limestone plateau dating back to the upper Cretaceous (ninety- one hundred million years ago) and rising 330 metres above sea level.
The area of Castellana is characterized by limestone, a sedimentary rock composed largely of calcium carbonate, known as Limestone of Altamura.
The cave system is 3348 metres in length and the point of maximum depth reaches 122 metres. The temperature within the caves is about 18 °C.
The caves are open all year round except for Christmas Day and the New Year’s day. The visit develops along two itineraries: the first is 1 km long and lasts about 50 minutes while the second is 3 km long and lasts about two hours. The tour timetable changes depending on the season. In addition, during the summer there are also guided night tours.
The Grave is the first and the biggest cave of this wonderful speleological complex and it is the only one communicating with the outside. It measures 100 m in length, 50 m in width and 60 m in depth. Going beyond the Grave stalactites, stalagmites, curtains and precious crystals continues to embellish everywhere the caves. The name of the environment are the result through the imagination of the early explorers: the She-Wolf, the Monuments, the Owl, the Little Virgin Mary, the Altar, the Precipice, the Desert Corridor, the Reverse Column, the Red Corridor, the Dome up to the last and the most dazzling one, the White Cave.