Mare Nostrum (English: Our Sea) is a 1948 Italian-Spanish drama film directed by Rafael Gil and starring María Félix, Fernando Rey and Guillermo Marín.

A Spanish sailor becomes mixed up with a mysterious foreign spy at the time of the Second World War.

It is an adaptation of the novel of the same name by Vicente Blasco Ibáñez which had previously been turned into a 1926 American silent film.

German spies, using Freya (María Félix) as bait, convince neutral Spaniard Ulysses Ferragut to navigate a ship to put naval mines around British ports in the Mediterranean, telling him they would never fire on passenger ships.

When U.S. troops take over Naples, Ulises chases the boss of the German spies, who is executed later.