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.
Bill Steele (cave explorer)
Continuing to explore caves throughout the United States, Steele led and participated in expeditions to Sistema Huautla in Mexico almost every year through the 1980s. In 1987, the Huautla expedition connected the deep cave Nita Nanta to Sistema Huautla; which established it as the second deepest cave in the world. Steele went to Kijahe Xontjoa on the plateau to the east of Huautla with an expedition of Swiss explorers in 1993, and explored depths over 1,000 meters.