The Una river: FAQ
Source, course, colour of the water and waterfalls.
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Source, course, colour of the water and waterfalls. 40 questions and answers for visitors to Bihać and the Una river.
Where is the source of the Una River?
The Una rises at Vrelo Une (the Una spring) near the village of Donja Suvaja in Croatia, below the slopes of Plješevica mountain and close to the border with Bosnia and Herzegovina. The spring is a round, blue-green karst pool. From there the Una flows towards Martin Brod and Kulen Vakuf, and then through Bihać.
How long is the Una River?
The Una is roughly 212 km long, though some sources give up to 214 km depending on how it is measured. It flows from its source near Donja Suvaja to its confluence with the Sava at Jasenovac. Its catchment covers about 10,200 km², most of it in Bosnia and Herzegovina.
Which countries does the Una River flow through?
The Una flows through Croatia and Bosnia and Herzegovina, and for long stretches it forms the border between the two. It rises in Croatia, most of its course runs through Bosnia and Herzegovina, and it joins the Sava on the border at Jasenovac. That is why along the Una you often cross from one bank, and one country, to the other.
Which towns are on the Una River?
Going downstream from the source, the Una passes Martin Brod and Kulen Vakuf, then flows through Bihać, Bosanska Krupa, Bosanska Otoka and Novi Grad. Further down it runs past Dvor, Kostajnica and Dubica, on both sides of the border, all the way to Jasenovac. Bihać is the largest town on the Una.
Where does the Una flow into the Sava?
The Una joins the Sava at Jasenovac, on the border between Croatia and Bosnia and Herzegovina. The confluence lies at about 95 metres above sea level, while the source is at around 400 metres. Along the lower course there are also old side channels that locals call Stara Una (the Old Una).
Why is the Una River so green?
The Una is emerald green to turquoise because its water is very clean and rich in limestone dissolved from the karst underground. Light refracts in the water and reflects off the pale riverbed and tufa deposits, so the river looks green or blue-green. The colour changes with depth, season and water level.
Why is the river called the Una?
According to a well-known legend, the name comes from Roman soldiers who, on first seeing the river, exclaimed 'Una', meaning 'the only one'. It is a folk tale rather than established historical fact, but it has become part of the river's identity. That is why the Una is still often described as 'the only one'.
What does 'Unski smaragd' (the Una emerald) mean?
Unski smaragd, 'the Una emerald', is a descriptive nickname for the Una and its emerald-green colour, used in tourism writing and everyday speech. It is not the official name of a protected area or an institution. The emerald colour is at its best in summer, when the water is low and clear, for example in Bihać and at Štrbački buk.
What is the water temperature of the Una River?
At the source the Una stays at roughly 8 to 11 °C all year. Downstream it warms up in summer, so in and around Bihać it is pleasant for swimming, though still colder than the sea. The exact temperature depends on the spot, the weather and the water level. Calmer stretches with shallows, like those in Lohovo and Pritoka, warm up the most in summer.
Can you swim in the Una River in Bihać?
Yes, in summer locals and visitors swim in the Una right in Bihać and in the surrounding villages. Calmer spots with shallows can be found in Lohovo and Pritoka, where many houses have their own access to the water. Inside Una National Park swimming is only allowed at designated spots.
Is the water in the Una River clean?
The Una is considered one of the cleanest rivers in the region, and in summer 2025 official tests confirmed that the water in Bihać was clean and safe. As with any river, quality can fluctuate briefly, especially after heavy rain. For up-to-date information, follow announcements from the City of Bihać.
Is the Una River protected?
Yes, several parts of the Una are protected. The Una spring and its surroundings were declared a natural monument back in 1968, and the upper course, together with its tributary the Unac, is part of Una National Park, established in 2008. Planned hydropower plants on the Una were dropped after strong opposition from local people and environmental groups.
How deep is the source of the Una?
Vrelo Une (the Una spring) is one of the deepest karst springs in Croatia and among the deeper ones in the world. Divers and researchers have reached about 248 metres, and the bottom has still not been found. The spring is protected as a natural monument. For visitors its appeal is its colour and stillness, while diving there is strictly for experienced cave divers.
Can I visit the source of the Una from Bihać?
Yes, you can drive from Bihać to the source of the Una near Donja Suvaja in Croatia, but you have to cross the border and allow for a longer drive through Lika. The roads to the spring are local and narrow in places. Check the route before you set off and bring your documents for the border.
What are the main tributaries of the Una?
The largest tributary of the Una is the Sana, which joins it at Novi Grad. The Unac meets the Una at Martin Brod, the Klokot near Bihać and the Krušnica near Bosanska Krupa. All of them are clear karst rivers. Each is worth a trip, and the Unac is part of Una National Park.
Where does the Unac flow into the Una?
The Unac flows into the Una at Martin Brod, inside Una National Park. It comes from the direction of Drvar and runs through a deep canyon along part of its course. Rmanj Monastery stands at the confluence, and Martin Brod is also home to the largest group of waterfalls in the park.
Are there waterfalls on the Una in Bihać?
Yes, both in Bihać itself and just outside town the Una forms rapids and small waterfalls over tufa steps. Downstream of town the best known is Kostelski buk, while upstream, in Ripač and Lohovo, there are several smaller falls. The largest waterfalls, Štrbački buk and Milančev buk, lie further upstream in Una National Park.
What are the most famous waterfalls on the Una River?
The most famous is Štrbački buk, 24.5 metres high and the largest waterfall on the Una. Next come the falls at Martin Brod, including Milančev buk, and Troslap and Dvoslap near Lohovo. All of them are in or next to Una National Park. Smaller falls and rapids can also be found in Bihać itself and downstream at Kostela.
What is tufa on the Una River?
Tufa (sedra) is a porous rock formed when limestone settles out of the water with the help of mosses and algae. On the Una it builds steps, waterfalls, cascades and small islands, so the river is constantly and slowly changing. That is why you should never walk on tufa barriers, as they are easily damaged.
Are there islands on the Una River in Bihać?
Yes, in Bihać the Una forms several islands and islets, including Gradska otoka and Ribička otoka. Upstream, near Ripač, are the well-known Japodian Islands (Japodski otoci), and downstream the Jotanovi otoci. The islands are lovely for a walk, a rest by the water and photos. The town islands are within walking distance of the centre, so they are ideal for a short stroll.
What are the Japodian Islands (Japodski otoci)?
The Japodian Islands are a group of small islands on the Una at Ripač, about ten kilometres upstream from Bihać centre. They are named after the Iapodes (Japodi), an ancient people who lived in this area and built pile dwellings by the water. Today they are a place for day trips, swimming and relaxing by the river.
Were there watermills on the Una River?
Yes, watermills worked along the Una for centuries, especially around the waterfalls. In the early 20th century there were mills beside Štrbački buk, and at Martin Brod you can still see old mills and bučnice, natural 'washing machines' for woollen cloth. Many have been restored as part of the local tourist offer.
What is a bučnica on the Una River?
A bučnica is an old wooden device in which the force of the river washes and softens woollen blankets and cloth. The water swirls the fabric around, which is why it is often called a natural washing machine. Martin Brod has a bučnica that is thought to be more than 300 years old.
What wildlife lives in and around the Una River?
The Una is home to brown trout, grayling and Danube salmon (huchen), and around thirty fish species have been recorded in the river and its tributaries. Otters and many birds live along the banks, while the surrounding forests shelter bears, wolves and lynx. The Una is also an important habitat for rare plants.
Which plant is named after the Una River?
The Una bellflower (unska zvončika), a rare bellflower with the Latin name Campanula unensis, is named after the river. It takes its name from the area along the Una, known for its turquoise and green water. Rare plants along the Una are protected, so please do not pick them. The Una bellflower grows mainly on rocks in the canyon and on the river's tufa banks.
Are there hydropower plants on the Una River?
Yes, there are older small hydropower plants on the Una and its tributaries, such as the Bihać plant from 1912 and the Kostela plant from 1952. In 2011 the Bihać power plant and its associated buildings were declared a national monument of Bosnia and Herzegovina. New, larger schemes on the upper course were rejected to protect the river.
What is the Una Regatta?
The International Tourist Una Regatta is the oldest and one of the best-known tourism and sports events in Bosnia and Herzegovina. Over several days, participants in boats and kayaks paddle down the Una, usually from Martin Brod towards Bihać and further downstream. It takes place at the end of July, and the 2026 edition was the 52nd.
When is the Una Regatta held?
The Una Regatta traditionally takes place at the end of July and lasts several days. In 2026 it ran from 22 to 25 July, opening at the Lučica camp near Martin Brod. Check next year's exact dates with the organisers, and book accommodation for the regatta early on apartmanibihac.com.
What route does the Una Regatta follow?
The regatta usually starts at Martin Brod and heads towards Kulen Vakuf and Štrbački buk, then on to Ripač and Bihać. The final stages run downstream of Bihać, towards the Cazin area and Bosanska Krupa. The stages can vary from year to year, so check the official programme.
Is there a riverside walk along the Una in Bihać?
Yes, Bihać has a riverside promenade along the Una that runs through the town centre, past the City Park and close to the Captain's Tower (Kapetanova kula) and the Fethija Mosque. The walk is flat and suitable for all ages. If you stay in an apartment in the centre, the promenade is just a few minutes' walk away.
What is the Una River like in winter?
In winter the Una is darker and often shrouded in mist, and the banks are quiet with no tourists. Because it is fed by a karst spring, the river rarely freezes, although ice sometimes forms along the edges. A walk by the river in snow and mist has a special atmosphere, but take care on the banks as the rocks are slippery.
When is the Una River at its highest and when is it clearest?
The Una is highest in spring, in April and May, when snow melts and there is more rain, and the waterfalls are at their most powerful. It is clearest in summer, when the water level drops and the river takes on its emerald colour. In autumn the level rises again after the rains.
Is the Una a dangerous river?
The Una is fast and cold in places and has waterfalls and rapids, so it calls for caution. On calmer stretches, such as in Lohovo and Pritoka, swimming is pleasant, but you should not go into the water near waterfalls and rapids. After heavy rain the current is faster and stronger, so it is better not to swim then.
How much of the Una River is in Bosnia and Herzegovina?
Most of the Una's course, from Martin Brod to its mouth, lies in Bosnia and Herzegovina or along its border with Croatia. The source and a short upper stretch are in Croatia. Because the border partly runs down the middle of the river, sources differ on the exact length of the section within Bosnia and Herzegovina alone.
What is the best base for exploring the Una River?
Bihać is the most practical base, as it sits in the middle of the most beautiful part of the Una, close to Una National Park and the Plitvice Lakes. To stay right by the water, choose a house in Lohovo, Pritoka or Grmuša. On apartmanibihac.com a whole apartment costs from €25, or 50 KM, per night, roughly the price of a single room in Bihać.
Does the Una River have beaches?
The Una has no sandy beaches like the sea; instead there are grassy banks, stony entry points and wooden bathing platforms. In Bihać people swim in summer at the town bathing spots along the promenade, and in Lohovo and Pritoka from grassy banks and shallows. Some properties, such as Farah Superior Apartments in Privilica, have their own private beach on the Una.
What is the Klokot River and where does it join the Una?
The Klokot is a short karst river, only a few kilometres long, that rises west of Bihać. It flows into the Una near the town. The Klokot spring is very abundant and is important for Bihać's drinking water supply. The spring is protected and there is a waterworks there, so access is partly restricted.
Why is the Una River so important to Bihać?
The Una is the symbol of Bihać, and the town grew up on its banks, with islands, bridges and a promenade through the centre. For centuries the river powered mills, and today it draws visitors with swimming, waterfalls, rafting and Una National Park. Most excursions from Bihać are linked to the Una in one way or another.
Is the Una River a UNESCO World Heritage Site?
The Una is not on the UNESCO World Heritage List. The tufa waterfalls at Martin Brod were added to Bosnia and Herzegovina's Tentative List in 2019, which is the first step towards a possible nomination. Una National Park has launched an initiative to extend the nomination to Štrbački buk as well.
What is the most beautiful part of the Una River?
Many consider the upper course the most beautiful, from Martin Brod via Kulen Vakuf and Štrbački buk to Bihać, most of which lies in Una National Park. That is where you find the largest waterfalls, canyons and tufa islets. From Bihać these places are between half an hour and about an hour's drive away.
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