This is a kind of transitional micro-region neighbouring the larger regions of Croatia - Gorski Kotar, Lika, Kordun and Gornje Pokuplje. The Ogulin-Modruš valley finishes towards the south where the Modruš hills pass into the second largest field of the area under Kapela-Plaški Polje. This comprises a completed geographical whole border on the western side by the mountain massif of Velika Kapela dominated by Klek (1181 m). Its eastern edges are bordered by the mounts of Krpel (), Brezovica () and Hum (). The valley then passes to the hilly are dominated by Klekinja () and Trojvrh (). This valley is also called Ogulin's Plain (in Croatian: Ogulinsko Polje). This is the fifth largest karst valley in Croatia (), and it lies above sea level. Its elongated form lies in the direction northwest-southeast, and it is long (Ogulin-Trojvrh) and wide (Desmerice-Skradnik). The Dobra River runs through and disappears in the center of the town. Approximately three kilometers south of the town centre is an artificial lake Sabljaci, formed with the purpose of accumulating water from the Zagorska Mrežnica river, and for the sake of generating electricity in the Hydroelectric power plant Gojak. The lake is connected with the town's other artificial lake, lake Bukovnik, via a tunnel. Lake Bukovnik is approximately one kilometer away from lake Sabljaci, and is connected to the hydroelectric power plant Gojak also with a tunnel, approximately 10 km long. The surface area of lake Sabljaci is around 170 ha, which makes it the 11th Croatian lake when compared by size. The lake contains many kinds of fish species, and it is also used for swimming and various water sports. According to the 2011 census, Croats comprise 80.2% and Serbs 17.7% of the municipality population. Serbs form a majority in many villages, most of them are upland. The settlements in the municipality are:  This church was built in 1781 in the middle of the town, in the Park of King Tomislav. Consecrated on June 1, 179, it reflects the spirit of the time with its pleasing external appearance and the richness of various sculptural decorations. The town of Ogulin celebrates September 14 as the fest day of its patron Saint of Extolling of the Cross.