The eastern boundaries of the Olfus county are limited to farm Alvidra and River Olfusa to the sea. The westernmost farm is Hlidarendi and the county engulfs the independent, horticultural town Hveragerdi and River Varma creates a part of the boundaries south of the Horticultural School and the excellent outdoor swimming pool at Laugaskard.
Close to the bridge across River Olfusa in town Selfoss a part of the county was contracted to the town in 1930 and in 1946 the Hveragerdi County was established and separated from the Olfus County. The county’s church sites are at Hjalli, Kotstrond and Thorlakshofn.
Communications within the county and connections with outside areas are good. The most important development was the opening of the Threngsli road (14,8 km) in the latter part of the 20th century and the inauguration of the Olfusa bridge (1988; 360m).