Unica (river)

Unica
Unica at the Planina confluence
Country	Slovenia
Basin features
Main source	underground confluence of the Pivka and the Rak in the Planina mountain cave 500 m (1,600 ft) 45°49′11.17″N 14°14′46.51″E / 45.8197694°N 14.2462528°E / 45.8197694; 14.2462528
River mouth	Vrhnika 308 m (1,010 ft) (underground)
Physical characteristics
Length	20 km (12 mi)
Discharge	Average rate: 13 m3/s (460 cu ft/s) (at the source in Planina Cave), 24 m3/s (850 cu ft/s) (at the outflow in Vrhnika)

Unica is a river in Slovenia. It starts as the underground confluence of the Pivka and the Rak in the Planina mountain cave. It forms the greatest confluence of underground rivers in Europe. 300 meter further Unica reaches overground near Planina. It then is about 10 km long. It has a northward direction of flow through Planina Polje (Planinsko Polje) over the municipalities of Postojna, Cerknica (Ivanje Selo) and Logatec (Jakovica), where it returns underground. It then flows for about another 10 km underground, emerging 142 m lower in multiple sources near Vrhnika to form the Ljubljanica river.