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.
John Volanthen
In 2004, Volanthen and Stanton set a world record for the greatest depth achieved in a British cave, cave diving at Wookey Hole in Somerset.
In 2010, Volanthen, Stanton, Jason Mallinson, and René Houben set a world record for the longest cave penetration dive, reaching in the Pozo Azul cave system in the Rudrón Valley in Spain.