Sea of Núrnen System
The Sea of Nurnen is a terminal sea, with no outlet rivers running to the ocean. Sea of Nurnen lies in the region of Nurn in the south of Mordor, in the middle of the sparsely vegetated plain of Lithlad (Ash Plain).
Since water leaves the lake only through evaporation, it leaves behind its dissolved minerals, making the sea up to 3 to 5 times saltier than the ocean. Nurnen has no fish, the largest aquatic critters are brine shrimp. The shrimp create one of the largest migratory bird magnets in Middle Earth. During the Third Age it is written that flies in Mordor were marked with the sign of the Red Eye.
The sea receives water from numerous perennial and intermittent streams originating in the surrounding mountains, the most important of which are four unnamed freshwater rivers. Two begin on the eastern side of the Ered Lithui (Ash Mountains), one from the eastern side of Ephel Duath and the last from the northern side of the Ephel Duath. These waters should have abundant fishing opportunities.