Surcouf had a twin-gun turret with 203 mm (8-inch) guns, the same calibre as the guns of a heavy cruiser, provisioned with 60 rounds. She was designed as an "underwater heavy cruiser", intended to seek out and engage in surface combat. The boat carried a Besson MB.411 observation floatplane in a hangar built aft of the conning tower for reconnaissance and observing fall of shot.
Surcouf had a twin-gun turret with 203 mm (8-inch) guns, the same calibre as the guns of a heavy cruiser provisioned with 60 rounds. She was designed as an "underwater heavy cruiser" intended to seek out and engage in surface combat The boat carried a Besson MB.411 observation floatplane in a hangar built aft of the conning tower for reconnaissance and observing fall of shot.