The Idrijca is a river flowing through the Idrija Hills and Cerkno Hills in Slovenia. It is 60 kilometres (37 mi) long.^[1] It rises near Vojsko, flows towards northeast and after passing through Idrija turns to the northwest. After passing through Spodnja Idrija and Cerkno it joins the Soča in Most na Soči. It has a pluvio-nival regime and belongs to the Adriatic Sea Basin.^[2]

Idrijca
The Idrijca near the Wild Lake
Location
Country	Slovenia
Physical characteristics
Mouth
• location	Soča
• coordinates	46°09′06″N 13°44′25″E / 46.1517°N 13.7404°E / 46.1517; 13.7404
Length	60 km (37 mi) [1]
Basin size	598 km2 (231 sq mi) [1]
Basin features
Progression	Soča→ Adriatic Sea

The river basin has an area of 598 square kilometres (231 sq mi).^[1] The major tributaries are the Belca, Zala, Cerknica, and Bača from the right and the Nikomlja, Kanošica, and Trebušica from the left. One of the right tributaries is also the Jezernica River, which originates from the Wild Lake (Slovene: Divje jezero). Being only 55 m long, the Jezernica is the shortest river in Slovenia.

The river has many fish, among which the Salmo marmoratus, the rainbow trout, and the Grayling are noteworthy. In the past, timber was driven down the Idrijca to Idrija to be used as pillars in the Idrija mercury mine. Special logging sluices (Sln. klavže) were employed for this purpose from the 17th until the 19th century.

The area of the upper Idrijca has been proclaimed the Upper Idrijca Landscape Park. It encompasses numerous karst features and diverse plant species. During World War II, Pavla Partisan Hospital stood there.