Vrtiglavica

Vrtiglavica, also Vrtoglavica (both from Slovene "vrtoglavica" 'vertigo'), is a karst shaft on the Kanin Plateau, part of the Kanin Mountains, Western Julian Alps, on the Slovene side of the border between Slovenia and Italy. It has the deepest single vertical drop in the world, at . The cave formed in a glaciokarst landscape; that is, a karst landscape that was subjected to Pleistocene glacial activity.
The total depth of the cave is . It contains one of the tallest cave waterfalls in the world; the estimated height of the falls is . It was discovered in the summer of 1996 by Italian speleologists and the bottom was reached on October 12, 1996, by a joint Slovene–Italian expedition.