The Trebisnjica is a river in Bosnia and Herzegovina. It used to be a sinking river, 96.5 km (60.0 mi) long above the ground. With a total length of 187 km (116 mi) above and under the ground, it is one of the longest sinking rivers in the world.
In classical antiquity, the river was known as the Arion, rising and sinking through its course before resurfacing at various places from the Neretva to the coast.
