The Myrdalur County is situated between the outwash plains Solheimasandur and Myrdalssandur and is the southernmost one in the country. Mountains and ridges divide the beautiful landscape and the largest valley, Myrdalur (The Boggy Valley), probably is the greenest spot of Iceland.

The mountainous area is indented with rugged canyons and gullies and crowned with the fourth largest glacier, Myrdalsjokull. At the valley's mouth, the southernmost point of the country, the promontory Dyrholaey, is situated.