Chemin de Fer de la Baie de Somme, Heritage railway in Somme Bay, France

The Chemin de Fer de la Baie de Somme is a metre-gauge heritage railway run by a non-profit association since 1970. Its two branches meet at Noyelles-sur-Mer: 7.5 km to Le Crotoy, opened in 1887, and 7.6 km to Saint-Valery-sur-Somme, opened in 1858 and laid with four rails since 1887. A steam locomotive with a red buffer beam marked "N°1" hauls brown carriages past the water.

The line was established in 1887 as part of a network serving seaside destinations, connecting rural towns and settlements. Originally it carried passengers, farm goods, and local materials like pebbles between communities along the coast.

The line's name comes from the Baie de Somme it skirts, and its metre-gauge cars and steam locomotives are restored by the non-profit CFBS, founded in 1970. Volunteers keep over 100 vehicles, including ten steam locomotives, in working order. A guest in 2016 was Harz narrow-gauge locomotive 99 6001.

The line runs from Le Crotoy via Noyelles-sur-Mer and Saint-Valery-sur-Somme to Cayeux-sur-Mer, with the Noyelles–Saint-Valery section laid as four rails of dual gauge. Board at Noyelles-sur-Mer, where the main-line station connects with the heritage trains, or at Saint-Valery-Port, rebuilt in 2011 with a water crane and turntable. The Noyelles–Le Crotoy line is 7,469 m long, with halts at Morlay and Favières.

At Noyelles-sur-Mer station, two different track gauges run side by side, allowing heritage trains and national railway services to operate in the same place. This technical arrangement is uncommon and shows how the local line was historically linked to the wider network.