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 603 metres (1,978 ft). The cave formed in a glaciokarst landscape, i.e. a karst landscape that was subjected to Pleistocene glacial activity.

The total depth of the cave is 643 m (2,110 ft). It contains one of the tallest cave waterfalls in the world; the estimated height of the falls is 400 to 440 m. It was discovered in summer 1996 by Italian speleologists and the bottom was reached on 12 October 1996 by a joint Slovene-Italian expedition.