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".
Harwood Hole
Harwoods Hole is a cave system located in the northwest of the South Island of New Zealand. It is one of several important cave systems in Takaka Hill, between Golden Bay and Tasman Bay. Starting at the surface as a 50-metre round entrance and descending 183 metres, Harwood Hole is New Zealand's deepest vertical shaft. Further in it connects with "Starlight Cave". The long rope descent is considered one of the most spectacular parts of the caving experience at Harwood's. Harwood's Hole has an overall depth of 357 m.