Boulogne-sur-Mer, often called just Boulogne, is a coastal city in Northern France. It is a sub-prefecture of the department of Pas-de-Calais. Boulogne lies on the Côte d'Opale, a touristic stretch of French coast on the English Channel between Calais and Normandy, and the most visited location in the region after Lille conurbation. Boulogne is its department's second-largest city after Calais, and the 163rd-largest in France. It is also the country's largest fishing port, specialising in herring.