The Mountain's Tongue, also known as the Mountain's Tongue River, is a long river fed by Lake Mountainwell, that begins in the mountains of the Moonlyt Peaks and flows south, eventually reaching the White Sea in the city of Faercrest. Along its path, life is dense, particularly in the Moonlyt Peaks; while the river has a wide watershed, the Peaks can seldom support agriculture or permanent cities elsewhere than on the banks of the Mountain's Tongue.
In winter, the river in the north is particularly notorious for freezing over in the north and causing a glacial dam, robbing many of much-needed water in the south. Discussion has also, on more than one occasion, led to the controversial possibility of a man-made dam being constructed, which would divert the water into the Moonlyt Valley and make the surrounding lands more fertile.
The Battle of Mountain's Tongue, a tertiary conflict in the 346 AC rebellion, took place on its banks, near the mountain range of the Moonlyt Peaks themselves.