Wild Lake is a lake near Idrija in western Slovenia and a karst spring of the Vauclusian type. The lake is the source of the Jezernica River, a tributary of the Idrijca and, at 55 m long, the shortest river in Slovenia. Water flows from under the ground and through a steeply inclined tunnel, explored to a depth of 160 m. The discharge occasionally surpasses 60 m3/s. However, when the water level is low, there is no outflow from the lake. In 1967, the lake was protected as a natural monument. In 1972, it was arranged to be the first Slovenian natural museum.