MN Surcouf (NN3) was a large French gun-armed cruiser submarine of the mid 20th century. She carried two 203mm guns as well as anti-aircraft guns and (for most of her career) a floatplane. Surcouf served in the French Navy during the Second World War. She was named after the French privateer and shipowner Robert Surcouf. She was the largest submarine built until surpassed by the first Japanese I-400-class aircraft carrier submarine in 1944.