Una is a river of special natural values as it is the one, only and unique (such as the old Romans named it – una). The spring is in Zadar county, some 100 km from Zadar, in Donja Suvaja which is close to the village of Srb. The area from which this unique river stars its journey has been declared a Hydrological monument of nature in 1968. The spring is at 398 meters altitude in a very narrow canyon where the water arises from great depths to the surface in a round, peaceful and blue-green form. The surrounding area of the spring is made up of forests and steep, high cliffs beneath the foothills of the mountains Plješivica and Stražbenica.