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.
Levan Maruashvili
Levan Iosifovich Maruashvili ( born 25 October 1912, Novocherkassk, Russian Empire, — 5 December 1992, Tbilisi, Georgia) was a prominent Georgian geographer. Doctor of Geographical Sciences (1954), professor (1965). Honored Scientist of the Georgian SSR (1966) and Abkhaz ASSR. Honorary member of the Russian Geographical Society (1985). He introduced a new concept of karst-sphere into the science. Krubera Cave, which is the world’s deepest known cave (2197 m), was discovered by the Georgian researchers in 1960 by the leadership of Professor Levan Maruashvili.