September the 9th, 2025 – Did you know that there’s a strange river in eastern Croatia that flows “backwards”? They say it has no source, and that it’s so calm the slightest little breeze can alter its flow.
As Putni kofer/Marina Hrupic writes, this river in Croatia has always been a huge part of local life and has been immensely important for the entire Slavonian plain. In addition, it has always represented a kind of natural phenomenon. Sometimes it was described as a “quiet and peaceful river whose plans could be disrupted by even the weakest breeze”. Due to its exceptionally calm flow, it was also often referred to as an apparently stagnant river. Since it doesn’t have the typical source that we’d expect, it’s also known for being a “river without a source”. This river in Croatia that flows “backwards” is the Bosut River, and it’s a truly interesting phenomenon.
it even fascinated the romans
The Romans were completely enchanted by it. According to legend, they used to boast that there was a river in their empire that flowed in one direction until noon, and in the afternoon, it flowed in the other. Of course, this was a picturesque allusion to its exceptionally calm and slow flow that the wind could play with without any effort. That’s precisely why this ultra-calm river in Croatia received the peculiar nickname “the river that flows backwards”. Sometimes, it really gave the impression that it was not flowing at all.
The Bosut, being so calm and slow, has an enviable length by Croatian standards. It is 186 kilometres long in total, and in addition to flowing through Croatian territory, it also flows through Serbia. The majority of its flow, 151 kilometres of it, is located in Croatia. It’s the fifth longest river in Croatia, but also one of the most underdeveloped and poorly known. It’s the longest left tributary of the mighty Sava, and it flows into it near the village of Bosuta in Serbia. Its main tributaries are the Biđ, Berava, Spačva and Studva.
a river without a source…
The Bosut is also special in that it is considered a river without a source. It rises between Štitar and Županja, and flows along a bed that was carved out long ago by one of the Sava River’s branches. “This arm split off below the mouth of the Bosna River, and returned to the Sava near the mouth of the Drina River. The upper entrance eventually silted up, probably from sediment from the Bosna River, meaning its bed was left without water and the Ottomans ended up naming it Bosut (meaning empty, with sut meaning water).
The first tributary on the left, the Berava, fills the bed with water, with many tributaries, streams and canals flowing into the Bosut itself. The old mouth eventually silted up, but the water broke through a new path about a hundred metres below the old one. A dam was also built there. They also say that the Bosut is formed by watercourses that flow from Dilje and Krndija by the merging of the Biđ and Berava streams, as well as underground springs.
vinkovci, one of europe’s oldest continuously inhabited towns, thrives alongside the bosut
Bosut, a so-called stagnant river, is also known for the fact that during periods of low water levels it can turn into a little jungle of aquatic plants. Due to a lack of oxygen, this can lead to the deaths of many fish, which are otherwise abundant in this river. Its banks are adorned with thick reeds, willows, and the remains of the ancient Bosut forests. This area is also home to various wetland birds, such as herons, wild ducks, and storks.
The Bosut has always been very important to local people. The largest settlement, or rather the town that thrives along this river, is Vinkovci, one of the oldest continuously inhabited cities in all of Europe. In Vinkovci, there is a promenade which stretches along the Bosut. It’s approximately four kilometres long, and leads from the centre to the popular Sopot resort.
