The Surcouf (N N 3) was a French submarine ordered to be built in December 1927, launched 18 October 1929, and commissioned in May 1934. Surcouf, named after the French privateer Robert Surcouf, was the largest submarine ever built, until being surpassed by the Japanese I-400. Her short wartime career was marked with controversy and conspiracy theories. She was classified as an "undersea cruiser" by sources of her time.
Surcouf was designed as an "underwater cruiser