The auxiliary ship Olterra was a 5,000 ton Italian tanker scuttled by her own crew at Algeciras in the Bay of Gibraltar on 10 June 1940, after the entry of Italy in World War II. She was recovered in 1942 by a special unit of the Decima Flottiglia MAS to be used as an undercover base for manned torpedoes in order to attack Allied shipping at Gibraltar.

Algeciras is a municipality of Spain belonging to the province of Cádiz, Andalusia. Located in the southern end of the Iberian Peninsula, near the Strait of Gibraltar, it is the largest city on the Bay of Gibraltar.