The Breg is a river in Baden-Württemberg, Germany. It is the right-side and longer of the two streams that form the river Danube. It begins at 1,078 m (3,537 ft) above sea level in the Black Forest, near Furtwangen im Schwarzwald, 100 m (330 ft) from the European Watershed. It flows through Furtwangen and Vöhrenbach.