07.10.2026
The northwest of Bosnia is held by two waters and two cities. Banja Luka stands on the Vrbas. Bihać stands on the Una. Between them are the forest of Kozara and a road that should not be measured by a motorway clock. Kastel is the fortress by the river. Štrbački buk and Martin Brod are the falls of the national park. The Japod islands are wooden footbridges and shallows near Bihać. This guide separates a city day from a river day, because joining them in one afternoon leaves both the quay and the falls unfinished.
Summer is the season of the Una. The water is cold, green and shallow enough to enter at the islands. Spring is fuller and louder. Autumn colours Kozara. In winter the falls remain and the swimming does not. Firms in Banja Luka are on the city map, and Bihać is on its own map.
Kastel is the fortress in Banja Luka, on the left bank of the Vrbas. The walls are not a backdrop behind a car park. They hold a walk that comes out onto the river. Inside there are exhibitions and events, but the reason to come is the meeting of stone and water. The city quay continues upstream and down. One afternoon covers the fortress and the bank if you do not rush toward the Una on the same day.
Banja Luka is a larger city than Bihać and asks for its own morning. Gornji Šeher and the older parts by the water are not the same frame as the centre. If you choose one hour, let it be the wall above the river, not a square without water.
The Vrbas runs through Banja Luka faster than a city street suggests. Upstream are the canyon, the rafters and colder water. In the city the bank is for walking, coffee and a view of the fortress. Do not mix the city quay with rafting. One is shoes on stone. The other is a boat and a guide. If you go upstream, ask who is leading that day, because the river is not the same after rain.
Štrbački buk is the stepped falls on the Una, inside the national park. The water whitens over travertine, and the path follows the bank. In summer the colour of the river is a reason to stay longer than one photograph. Shoes must hold wet stone. Do not climb down where the fence and the warden say not to. The park has rules that are not decoration on a board.
From Bihać this is an outing, not a pause between two coffees. Martin Brod is another falls, the other end of the same park. Joining them is worth it if the day belongs to the Una, not if the day also belongs to Banja Luka.
Martin Brod is a settlement and a set of falls on the upper Una, closer to the entrance of the park from that side. The water splits into arms and falls in several streams. The walk is shorter than a whole day, but the road to it is not. In summer the shade by the river is precious. Autumn is quieter. In winter ask whether the road is open before you leave Bihać on an assumption.
The village is not a museum. The houses by the water have people in them. Stay on the path and in the places where entry is meant.
The Japod islands are on the Una near Bihać. Wooden bridges link small islands, and in summer the water is calm enough to enter. This is a city outing, closer to a coffeehouse than to Štrbački buk. It is therefore a good end of the day, when the falls have already been seen or when the day cannot take a long road. Do not leave rubbish on an island. The river here runs through someone else's city and your own at the same time.
Kozara is a forested mountain between Banja Luka and the Una, a national park with paths and a viewpoint. It is not a waterfall and it is not a fortress. The visit makes sense if you want beech and a view, not yet another green river. The paths are marked, but fog and mud do not read the board for you. One shorter climb to the view covers a morning. The whole ridge asks for a full day and does not fit beside Štrbački buk.
The Krajina cannot be reduced to one postcard. A city on the Vrbas, a city on the Una and one water that falls already make an honest weekend. The firms by the quay and by the park stay in the directory, with a door, and not as a name without an address.
