The terrain of Haakon County consists of semi-arid rolling hills, carved with gullies and drainages, partially devoted to agriculture. The Cheyenne River, a tributary of the Missouri River, flows northeastward along the county's north boundary line, and the Bad River flows east-northeastward through the lower part of the county, both heading for their discharge points into the Missouri. The terrain slopes to the northeast, and its highest point is near the midpoint of its western boundary line, at 2,802' (854m) ASL.