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".
Yarlung Tsangpo Grand Canyon
The Yarlung Tsangpo Grand Canyon or Yarlung Zangbo Grand Canyon () or simply the Tsangpo Canyon, Brahmaputra Canyon or Tsangpo Gorge, along the Yarlung Tsangpo River in Tibet Autonomous Region, China, is the deepest canyon in the world, and at 504.6 km (314 miles) is slightly longer than the Grand Canyon in the United States, making it one of the world's largest. The Yarlung Tsangpo (Tibetan name for the upper course of the Brahmaputra) originates near Mount Kailash and runs east for about 1700 km, draining a northern section of the Himalayas before it enters the gorge just downstream of Pei, Tibet near the settlement of Zhibe. The canyon has a length of about 240 km (150 miles) as the gorge bends around Mount Namcha Barwa (7782 m) and cuts its way through the eastern Himalayan range. Its waters drop from about 2,900 m near Pei to about 1,500 m at the end of the Upper Gorge where the Po Tsangpo River enters. The river continues through the Lower Gorge to the Indian border at an elevation of 660 m. The river then enters Arunachal Pradesh and eventually becomes the Brahmaputra.