Andorra is situated in a single drainage basin, but its main stream, the Riu Valira, has two distinct branches and six open basins; hence the term "Valleys" (Les Valls) was traditionally employed as part of the name of the principality. The section of the river flowing through El Serrat by way of Ordino and La Massana is the Valira del Nord, while that flowing through Canillo, Encamp, and Les Escaldes is the Valira d'Orient. Most of the country is rough and mountainous, and there is little level surface. All the valleys are at least 900 m (3,000 ft) high, and the mean altitude is over 1,800 m (6,000 ft). There are lofty peaks, of which the highest is Coma Pedrosa (2,946 m/9,665 ft).