The River Trebišnjica, once the largest losing streams in Europe, is 98 km long, and its total length, above and under the ground, is 187 km. Trebišnjica flows through Gatačko field (Mušnica and Gračanica) Cerničko field (Ključna River) and Fatničko field. The River Fatnička emerges in strong springs near Bileća, where Trebišnjica is formed. The Trebišnjica River emerges as the spring of the River Ombla near Dubrovnik, and the largest part flows off underground into Neretva River. One of the attractions, characteristic of the River Trebišnjica, is jumping off the bridge, which is traditionally held every summer.