During its watercourse Tara cuts one of the deepest canyon cliffs in the world, for more than 78 km in lenght. Her vertical steep sides are more than 1300 meters tall, which makes Tara canyon deepest in Europe. This canyon is on the list of 25 most significant world natural heritage sites. It is under the protection of UNESCO since 1977. Tara is the longest river in Montenegro - 144 km. It springs from the bottom of mountain Komovi and is constituted from streams Opasanica and Veruša and melting snow and seasonal rains. Just near BiH near Šćepan polje it is joining river Piva, and together river Drina is formed. Drina flows into Sava which then flows into Danube which is confluent of Black Sea basin.