Pyramid Lake is the geographic sink of the Truckee River Basin, 40 mi (64 km) northeast of Reno. Pyramid Lake is fed by the Truckee River, which is mostly the outflow from Lake Tahoe. The Truckee River enters Pyramid Lake at its southern end. Pyramid Lake has no outlet, with water leaving only by evaporation, or sub-surface seepage (an endorheic lake). The lake has about 10% of the area of the Great Salt Lake, but it has about 25% more volume. The salinity is approximately 1/6 that of sea water.