France Commissions 'Tourville' Third Suffren-Class Nuclear-Powered Attack Submarine into Service

On July 4, 2025, the French Navy officially welcomed its third Suffren-class nuclear-powered attack submarine (SSN), Tourville (S637), into active duty. This development marks a significant enhancement in France’s naval strength amid increasing tensions and underwater activity in European waters.

The Tourville, part of the Barracuda program, is one of six next-generation submarines being built to replace the aging Rubis-class fleet. Designed and constructed by Naval Group at its Cherbourg shipyard, Tourville was rolled out in July 2024 and handed over to the Navy in November 2024. Since then, it has undergone extensive sea trials, testing its endurance, equipment performance, and operational readiness under various conditions—from the Atlantic to the Caribbean and as far north as Halifax, Canada.

These trials, known as Verification of Military Characteristics, are equivalent to the shakedown cruises used in other navies. During the process, Tourville operated in both cold and warm waters, allowing the crew to fine-tune systems under real-world conditions. The Canadian port visit also served a diplomatic and strategic purpose, as Canada is currently evaluating options to replace its Victoria-class submarines—with the French design considered a contender.

French Minister of Armed Forces Sébastien Lecornu, speaking at the induction ceremony, described the commissioning as timely, especially as underwater warfare and clandestine operations are more active now than at any time since the Cold War. He highlighted the growing threat posed by an increasingly capable Russian submarine fleet, which still retains Cold War-era expertise in undersea operations.

The Tourville’s induction also coincides with infrastructure upgrades in France. The opening of a second submarine dock (MY02) at the Cherbourg naval base will enable the French Navy to house and maintain two Suffren-class SSNs simultaneously. This is part of the Barracuda Support Infrastructure Programme (PI ASB), which also supports future maintenance of the Rubis-class until their retirement and the nuclear systems aboard the aircraft carrier Charles de Gaulle.

Suffren-Class: The Backbone of France’s Future Submarine Force

The Suffren-class SSNs are a huge technological leap over their Rubis-class predecessors. Each submarine displaces around 5,100 tons submerged, is 99 meters long, and can dive to depths of more than 350 meters. Powered by a 150 MW pressurized water reactor, these submarines can remain at sea for up to 70 days, limited only by food supplies.

They are equipped for a wide range of missions—anti-ship warfare, anti-submarine warfare, intelligence gathering, long-range strikes, and special operations. Armament includes F21 heavyweight torpedoes, Exocet SM39 anti-ship missiles, FG-29 naval mines, and the MdCN naval cruise missile, which can be launched from torpedo tubes to strike deep inland targets while staying hidden beneath the ocean.

One of the standout features of the class is its Dry Deck Shelter, enabling deployment of special forces using swimmer delivery vehicles such as the PSM3G. The class also incorporates non-penetrating optronic masts, developed by Safran, which deliver ultra-clear 4K imagery and can be accessed by all command personnel, revolutionizing how information is shared onboard.

With Tourville now in active duty, France has three out of six planned Suffren-class submarines operational, significantly modernizing its undersea warfare capabilities. As the geopolitical climate continues to evolve, particularly in the Atlantic and Mediterranean regions, France’s ability to project power discreetly and effectively beneath the waves has just taken a powerful step forward.