The Sienne (French pronunciation: [sjɛn]) is a 92.6 km (57.5 mi) long river in northwestern France located in the departments of Calvados and Manche, Normandy. It flows into the English Channel near Regnéville-sur-Mer. Its longest tributaries are the Soulles and the Airou. The largest towns on the Sienne are Villedieu-les-Poêles and Quettreville-sur-Sienne.