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.
Macocha Gorge
The Macocha Abyss (Czech: "Propast Macocha", literally the "Stepmother Abyss"), also known as the Macocha Gorge, is a sinkhole in the Moravian Karst cave system of the Czech Republic located north of the city of Brno, near the town of Blansko. It is part of the Punkva Caves and the Punkva River flows through it. The sinkhole is about 138.7 meters deep, which makes it the deepest of its kind (light hole type) in Central Europe.
It is a popular tourist attraction for casual visitors to the region, in addition to cavers and advanced technical divers.