The River Surbrin flows from the Spine of the World to join the River Rauvin, forming the River Surbin. The River Surbrin flows only a few miles to the east of Mithral Hall, north to south along the eastern edge of the Spine of the World. The town Nesmé sits on the eastern side of the River Surbrin, with a large fortified bridge across to the stronghold of the Riders of Nesmé.