The Una Spring is located at 395,8 meters above sea level in the part of Lika belonging to the Zadar County, under the slopes of Lička Plješivica and Stražbenica, in the vicinity of Donja Suvaja, located in the Municipality of Gračac.
The spring of Una is a fairy tale turquoise-coloured lake surrounded by forests and steep cliffs. With its calm surface, this lake is one of the deepest and strongest springs of this area. The first Una waterfall is located some 10 meters from the spring.
In 2007, the lake was explored by cave divers who participated in an international expedition. An Italian cave diver named Luigi Casati reached the depth of 205 m and took photographs of this natural phenomenon.
Thanks to its incredible beauty and exceptional hydro-morphological value, in 1968 the lake and the canyon surrounding it, as well as 150 meters of downstream flow were named a protected hydrological monument of nature.