If you happen to be on a road-tripping across the hinterlands of the Bosnian Adriatic coast, particularly around Trebinje, a city that once charmed Napoleon, you don’t want to miss the most spectacular gem of nature that this region has to offer – the Trebišnjica River. It is a unique phenomenon that crosses the valley of Popovo Polje and consists of many above and underground watercourses. On its way to the Adriatic Sea, the river, once called the Arion, flows underground and reappears many times on the surface. With a total length of 187 km, and half of it below the ground, Trebišnjica is the world’s longest sinking river. It is also a remarkable hydroelectric power in this part of the country. The place where this river emerges in its full beauty is Trebinje.
The river of Trebišnjica originates from two streams coming from the Mt. Lebršnik and Mt. Čemerno, in the southeastern region of Bosnia & Herzegovina, close to the border with Montenegro. Those streams are flowing through three karst fields – Gatačko, Cerničko and Fatničko Polje. After almost 50 km of the underground flow, the water emerges as multiple cave springs near the town of Bileća, shortly joined as the Trebišnjica River, before being flooded by Bileća Lake. The largest underground river, 98 km long, flows further through the karst fields of Popovo Polje, known as the Provence of Bosnia & Herzegovina, where the water sinks and emerges as three different outflows.
One of the outflows appears as spring of Čapljina, in the lower region of the Neretva River. Another place where this river emerges in the form of warm springs is close to the small seaside town Slano in Croatia. Finally, after 20 km of the underground flow towards the south, the Trebišnjica re-appears near the cave Gruž, like a spring of the river Ombla in Dubrovnik.
The river of Trebišnjica represents a huge water potential, not sufficiently exploited. Often along the river, one can see the old mills, a sort of local attractions typical for this region. Thanks to its peaceful flow and crystal-clear water, this river is an ideal location for many sports activities such as diving and fishing. If fishing is your thing, you would like to know that some endemic species of fishes, including famous olm (proteus), can be found here. But if you are more into adrenaline raising sports, kayaking is a great option to try out, or jumping off the bridge, if you come during the summertime.
The best place to admire the beauty of Trebišnjica is the city of Trebinje that this river splits in two. The watercourse of Trebišnjica, world’s longest sinking river, is crossed by many bridges, but three of them are standing out thanks to its outstanding beauty. Besides Ivo Andrić bridge and Stone bridge in Trebinje, the one that steals the glory is, by all means, a 16th- century masterpiece - Arslanagić bridge.