Lijak is a strong but irregular karstic spring of the stream of the same name flowing from below the precipitous edge of the Trnovo Forest.
In the rocky slope above Lijak there is a natural bridge (15 m long and 10 m high) with a grotto called Skozno which offers a beautiful view of the Vipava Valley and the Friuli region. The bridge can be accessed by the track departing from the south of the village Trnovo. The area surrounding the Lijak stream is protected as a natural monument.
GPS Northing (N) : 45,9577
GPS Easting (E) : 13,7169