Vrtiglavica, also Vrtoglavica, 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 known pitch in the world, at 603 metres (1,978 ft). The cave formed in a glaciokarst landscape; that is, a karst landscape that was subjected to Pleistocene glacial activity.