Western tributaries of the Gudbrandsdalslågen include the Gausa River flowing through the Gausdal valley, the Otta River flowing through the Ottadalen valley, the Vinstra River flowing through Vinstradalen, and the Sjoa River, flowing through the Heidal valley. The eastern rivers, Jora, Ula, Frya, Tromsa, and Mesna are shorter and drop precipitously from the heights of the Rondane mountains. Although relatively placid for extended stretches of its 204-kilometre (127 mi) path, the Gudbrandsdalslågen drops rapidly through the Rosten Gorge in Sel Municipality.[2]