The Blies is a right tributary of the Saar in southwestern Germany (Saarland) and northeastern France (Moselle). The Blies flows from three springs in the Hunsrück near Selbach, Germany. It is approximately 100 km long, ending in the French city of Sarreguemines. It flows through Sankt Wendel, Neunkirchen, and Blieskastel (one of several towns named after the river). Its lower course forms the border between France and Germany.