Portneuf-sur-Mer is a municipality in the Côte-Nord region of the province of Quebec in Canada. The municipality is located at the mouth of the Portneuf River on the St. Lawrence River.

Area codes 418, 581, and 367 are telephone area codes in the North American Numbering Plan (NANP) for the eastern portion of the Canadian province of Quebec. Area code 418 was originally assigned to the numbering plan area, but all three area codes now form an overlay plan for this territory. Cities in the numbering plan area include Quebec City, Saguenay, Lévis, Rimouski, Saint-Georges, Alma, Thetford Mines, Sept-Îles, Baie-Comeau and Rivière-du-Loup. Also served are the Gaspé Peninsula, Côte-Nord, southeastern Mauricie, and the tiny hamlet of Estcourt Station, in the U.S. state of Maine.