Lake Rødenessjøen is located in the Marker Municipality and is one of the deepest in the Haldenvassdraget. In the north, it becomes Lake Skulerudsjøen on the border of Akershus and Østfold Counties.
A fjordlike lake, it has a narrow fringe of forest down to the shoreline before the dark land takes over. Thus the impression from the water is of a true wilderness. The large pike in the lake is well established and joins perch and burbot as the most important fish species.