The French Navy’s (Marine Nationale) third Suffren-class nuclear-powered attack submarine (SSN) Tourville (S637) entered “active duty” (admission au service actif in French) on July 4th, 2025.
Sebastien Lecornu, French Minister of Armed Forces stated:
“Today, the Tourville nuclear-powered attack submarine enters active duty. This is the third of six Barracuda-class nuclear-powered attack submarines that will upgrade our capabilities to the highest standard.”
Tourville was rolled out of the submarine construction hall at the Naval Group shipyard in Cherbourg on July 20th, 2024 and was delivered in November 2024.
Tourville‘s admission to active duty comes after sea trial phases which started in July 2024. These phases of Verification of Military Characteristics (also known as shakedown cruises in the US) allow the crew to test the performance and endurance of the vessel as well as the conformity of the equipment to the requested specifications.
During these tests which lasted three months, Tourville sailed in cold and warm waters mainly in the Atlantic Ocean. It sailed off the Portugal, joined the Caribbean and went North until Halifax in Canada in March 2025 where the submarine made a stopover. This port call enabled the Canadian authorities to visit the ship as the latter is among the contenders to replace the Victoria-class.
The triggering of the active duty for the third submarine comes in a more tense geopolitical context as underwater warfare and grey operations near France’s coasts are the most active since the end of the Cold War. To cope with those, the increased capabilities of the Suffren-class brings an unprecedented upgrade to the French submarine flotilla and fills up a certain gap in these domains.
During a speech delivered during the ceremony, the MoD stressed how the Barracuda type SSN comes at the right time, especially to face a Russian submarine fleet as sharp as ever:
“While it has to be said that Russia has not always shined for the efficiency of its Navy and surface vessels, it has to be said in all honesty that its submarines are the repository of know-how that goes back to the Cold War.”
This ceremony was also an opportunity to officialise the opening of a second dock (MY02) able to host two Suffren-class submarines simultaneously. This is part of a larger infrastructure plan “Barracuda Support Infrastructure Programme (PI ASB) consisting in modernising docks, basins, networks and support buildings. Because of their extended size compared to their predecessors, they require adapted infrastructures specific to their technical requirements, as well as to the nuclear safety standards that have been tightened since Fukushima. It will enable the Suffren type submarines to be maintained and to provide residual support for the Rubis-class until their full retirement in 2030. It also guarantees support for the boiler rooms of the Charles-de-Gaulle aircraft carrier for its overhaul in 2027.
In October 2021, Naval News was granted access to the first-in-class submarine Suffren and experienced what it is like to step inside a next-generation nuclear-powered attack submarine. Click here to read a more in-depth article about Suffren.
About Suffren-class SSN
Six new attack submarines will form the vanguard of the French Navy (Marine Nationale) for the coming decades. Developed as part of the Barracuda program, the lead boat of the new class, Suffren, was launched in July 2019. The new submarines will offer a massive capability leap over the current Rubis-class boats.
Suffren in numbers:
- Surface displacement: 4,700 tons
- Diving displacement: 5,100 tons
- Length: 99 meters
- Diameter: 8.8 meters
- Maximum depth: > 350 meters
- Speed: > 25 knots
- Armament: naval cruise missiles, F21 heavy-weight wire-guided torpedoes, modernized Exocet SM39 anti-ship missiles, FG-29 mines, D-19 UUV (future development)
- Hybrid propulsion: pressurized water reactor (150MW) derived from the reactors on board the Triomphant-class SSBN and Charles-de-Gaulle aircraft carrier, two propulsion turbines, two turbo generators and two electric motors
- Crew: 63 crew members + approx. 15 commandos
- Endurance: 70 days at sea (or until food supplies run out)
Innovation for naval combat
Suffren-class SSNs are equipped with numerous innovations that allow them to demonstrate differentiating capabilities in many areas. The French Navy’s new class of submarines is able to strike deep behind enemy line all while remaining stealthy thanks to the torpedo tube-launched naval cruise missile (MdCN). The integration of state-of-the-art sensors also gives it superior anti-submarine warfare and intelligence, surveillance, reconnaissance (ISR) capabilities. The non-penetrating optronic masts (by Safran Electronic and Defense) are a disruptive technology. They bring unmatched high quality (4K) imagery and every sailor in the CIC can access them. Finally, these submarines comes with systems that facilitate the deployment of naval special forces. In particular, the Dry Deck Shelter, a removable deck hangar, allows the deployment of the new PSM3G swimmer delivery vehicle (SDV) and a dozen combat swimmers.
