Divje jezero ('Savage Lake') is a karst siphon lake which is situated about 2 km southern from town Idrija. The lake is at the bottom of the stony kettle below hundred metres high precipice which border the northern plateau named 'Črnovska panota'. The lake is also a karst spring and water is flowing from the underground and steep sweeping tunnel. The tunnel has been explored 160 metres deep. From the lake-karst spring flows the shortest above ground river in Slovenia - only 55 m into river Idrijca. Tempreature of the water is between 7 and 10C° in all seasons of the year. The lake was protected as a nature monument in 1967 and access was set up for visitors since 1972 as the first museum in nature.