نهر ديالى
A large portion of the province is drained by the Diyala River, a major tributary of the Tigris. Because of its proximity to two major sources of water, Diyala's main industry is agriculture, primarily dates grown in large groves. The province also contains one of the largest olive groves in the Middle East. It is also recognized as the orange capital of the Middle East. The Hamrin Mountains pass through the governorate.