The Rak is a stream in Inner Carniola, a traditional region of southeastern Slovenia. It sources in Zelše Caves (Zelške jame) west of the village of Zelše, flows across the Rak Škocjan karst valley for 2 kilometres (1.2 mi) and enters Weaver’s Cave (Slovene: Tkalca jama), where it continues for 3 kilometres (1.9 mi) and merges in Planina Cave (Planinska jama), about 300 metres (980 ft) from its entrance, with the Pivka River to form the Unica.
The confluence of the Rak and the Pivka is one of the largest subterranean confluences in Europe.
