Le Redoutable (S 611) was the lead boat of her class of ballistic missile submarines in the French Marine nationale.
Commissioned on 1 December 1971, the boat was the first French SNLE (Sous-marin Nucléaire Lanceur d'Engins, "Device-Launching Nuclear Submarine"). The boat was initially fitted with 16 M1 MSBS (Mer-Sol Balistique Stratégique) submarine-launched ballistic missiles, delivering 450 kilotons nuclear warheads at . In 1974, the boat was refitted with the M2 missile, and later with the M20, each delivering a one-megatonne warhead at a range over . Le Redoutable ("formidable" or "fearsome" in French) was the only ship of the class not to be refitted with the M4 missile.
Le Redoutable had a 20-year duty history, with 51 patrols of 70 days each, totalling an estimated 90,000 hours of diving and of distance, the equivalent of travelling 32 times around the Earth.
The boat was decommissioned in 1991. In 2000, the boat was removed from the water and placed in a purpose-built dry dock,