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".
Ghar Parau
A British led caving expedition to the Zagros Mountains in 1971 led to the discovery of the cave. The cave was explored to a depth of 742 m by the time the expedition was forced to return to the surface. The explorers believed that the cave might go on much further, possibly surpassing the Gouffre de la Pierre-Saint-Martin system, which at that time was the world's deepest known cave.