Croatian border after about 8 km. This time, the river forms the border for about 18 km and cuts through a gorge, forming a cascade of rapids and waterfalls, the biggest and most notable being the Štrbački buk. After entering Bosnia completely for the second time, the rivers forms the Troslap and Dvoslap waterfalls, after which it exits the national park and flows through the villages of Lohovo and Račić. After that, the river slowly enters the Bihać field, flowing through the villages of Ripač, Golubić and Pritoka, taking in the waters of the Dobrenica and forming multiple river islands and small waterfalls, before finally entering the city of Bihać after about 70 km of total flow. In Bihać, the river forms multiple islands of varying sizes, often surrounded by small waterfalls, some of which are private property while others are public and often popular bathing sites. The core of the city itself is surrounded by the Una river, and a channel carries water from the river to a small hydroelectric power plant. Another small tributary of the Una, the Drobinica, flows through the city in a regulated channel before merging with the Una. In its upper course, the Una is a youthful river with a steep gradient of 0.232% and a large amount of waterfalls. The total drop is over a distance of . The deposition of carbonate minerals and the formation of porous limestone rock (tufa) and pronounced karst influence is characteristic for this section. Middle course The middle section of the river spans from the city of Bihać to the town of Novi Grad and its confluence with the Sana. Not long after exiting the city the river takes in the waters from the short Klokot river, after which it meanders, slowly turning eastward before entering the village of Pokoj where it takes a sharp turn north and enters a canyon between Bihać and Bosanska Krupa where it slowly turns eastward again. The Una Kostela hydroelectric power plant is located not long after the entrance into the canyon and is currently one of two hydroelectric power stations on the main course of the river, the other being the small Bihać power plant. The canyon is, on average, around deep with lush vegetation growing on its cliffs. A road that connects Bihać and Bosanska Krupa follows the river through the canyon. After flowing for about 27 km through