Velebit
There are hundreds of "holes" on Velebit. It has the largest and deepest caves in Croatia. The three-part "Lukina jama" cave is 1392 m deep, making it one of the deepest caves in the world, and the deepest in southeast Europe, while the "Slovačka jama" is 1320 m. What makes it unique is that it is completely vertical, steepest in the world. At the bottom of the pothole is a water course or siphon with branches that are still unexplored. A kind of leech was discovered in the pothole, which has been ascertained to represent a new species, genus and family; it has been named "Erpobdella mestrovi".
Lamprechtsofen
On August 19, 1998, a team led by Polish caver Andrzej Ciszewski discovered a connection between Lamprechtsofen and the PL-2 cave system, which established the height difference of the united cave system as . This new discovery made Lamprechtsofen the deepest-known cave in the world for less than three years, since Krubera was discovered in June 2001 to be deep.