The Aran Valley (Occitan: Era Val d'Aran; Catalan: la Vall d'Aran; Spanish: El Valle de Arán) is a small valley (620.47 km²) in the Pyrenees mountains and a comarca (county) in the northwestern part of Catalonia, Spain. Most of the valley constitutes the only part of Catalonia on the north face of the Pyrenees, hence the only part of Catalonia whose waters drain into the Atlantic Ocean. The region is characterized by an Atlantic climate, due to its peculiar orientation, which is different from other valleys in the area.