BETASOM was a submarine base established at Bordeaux, France by the Regia Marina Italiana during World War II. From this base, Italian submarines participated in the Battle of the Atlantic from 1940 to 1943 as part of the Axis anti-shipping campaign against the Allies.

Bordeaux is a city on the river Garonne in the Gironde department, southwestern France. A port city, it is the capital of the Nouvelle-Aquitaine region, as well as the prefecture of the Gironde department. Its inhabitants are called "Bordelais" (masculine) or "Bordelaises" (feminine). The term "Bordelais" may also refer to the city and its surrounding region.