The military submarine: the ultimate weapon of the deep
The military submarine is undoubtedly the most formidable and mysterious weapon in the modern arsenal. Capable of moving in complete secrecy hundreds of meters below the surface, remaining submerged for weeks or even months, and striking thousands of kilometers away, it embodies naval power in its most absolute form.
France is among the very small circle of nations—barely six in the world—capable of designing, building, and operating nuclear-powered submarines. It is Naval Group , France's leading naval industrial group, which designed and built these technological marvels in Cherbourg and Brest. This comprehensive guide explains everything: the different types of military submarines, the French fleet, their staggering costs, and the extraordinary lives of their crews.
The different types of military submarines
There are several major categories of military submarines, classified mainly according to their propulsion system and primary mission.
The SSBN Nuclear-Powered Ballistic Missile Submarine
The SSBN represents the pinnacle of undersea military power. Its sole and permanent mission is to provide the ocean-based component of France's nuclear deterrent. At all times, one of France's four SSBNs of the Le Triomphant is on patrol somewhere in the world's oceans, ready to fire its M51 ballistic missiles, capable of reaching any target on Earth. This is what is known as the FOST — Strategic Oceanic Force . This submarine is the ultimate guarantor of France's sovereignty and survival.
The SSN Nuclear-Powered Attack Submarine
Smaller and more agile than the SSBN, the SSN is the hunter of the deep. Its nuclear propulsion gives it virtually unlimited endurance—the crew's food supplies are the only factor limiting patrol duration. It can track and destroy enemy submarines, escort SSBNs, carry out precision strikes with cruise missiles, and gather intelligence undetected. France currently operates the Rubis and is gradually introducing the new class Suffren (Barracuda program) , which is significantly more capable.
The conventional diesel-electric submarine
Less expensive than nuclear submarines, diesel-electric submarines make up the vast majority of the world's fleets. France has abandoned them for its own navy but exports them successfully through the Scorpène from Naval Group — notably sold to Brazil, India, Chile, and Malaysia. Their endurance is more limited (a few weeks), but their acoustic discretion can be superior to that of nuclear submarines under certain conditions.
How many military submarines does France have?
France has a fleet of military submarines 100% nuclear-powered , placing it in a category of its own in Europe. Here is the detailed composition of the French submarine fleet in 2025.
| Type | Class | Number | Propulsion | Primary role |
|---|---|---|---|---|
| Ballistic missile submarine | Le Triomphant | 4 | Nuclear | Nuclear deterrence |
| Attack submarine | Rubis | 4 (in service) | Nuclear | Attack / Intelligence |
| Future attack submarines | Suffren (Barracuda) | 6 (on order) | Nuclear | Replacement Rubis |
Source: French Navy — Ministry of the Armed Forces 2025.
In total, France has 8 nuclear military submarines in service or currently being delivered. The four Le Triomphant-class ballistic missile submarines ensure France's continuous ocean-based nuclear deterrence. The Rubis-class attack submarines are gradually being replaced by the much more capable Suffren submarines of the Barracuda program—the first, Suffren , was delivered in 2022.
How much does a military submarine cost?
This is one of the most frequently asked questions—and for good reason: the figures are staggering. A military submarine is one of the most valuable objects ever built by humans, concentrating decades of technological research in a confined space subject to extreme constraints.
| Submarine type | Country / Builder | Estimated unit cost | Propulsion |
|---|---|---|---|
| Le Triomphant-class ballistic missile submarine | France / Naval Group | €3 to €4 billion | Nuclear |
| Suffren-class attack submarine (Barracuda) | France / Naval Group | €1.5 to €2 billion | Nuclear |
| Scorpène (export) | Naval Group | €400 to €700 million | Diesel-electric |
| Virginia (United States) | General Dynamics | ~€3.5 billion | Nuclear |
Sources: Naval Group — French Court of Audit — publicly available estimates.
These construction costs are supplemented by maintenance and operational-readiness costs, which over the submarine's entire service life (30 to 40 years) often exceed the initial purchase price. A ballistic missile submarine therefore costs several tens of billions of euros over its entire life cycle.
Why does it cost so much?
The technological complexity of a nuclear submarine is comparable to that of a nuclear reactor mounted in a rocket capable of diving to a depth of 400 meters. The materials used (high-yield-strength steel, pressure-resistant equipment), underwater navigation systems without GPS, ultra-sensitive passive sonars, and integrated weapons systems each represent multiyear R&D programs. On average, it takes 7 to 10 years to build a ballistic missile submarine.
Life aboard a military submarine
Living and working aboard a military submarine is an extraordinary experience, reserved for carefully selected and trained elite sailors. A patrol aboard a ballistic missile submarine lasts an average of 70 days without ever surfacing, without communicating with their families, in a confined living space shared with around a hundred colleagues.
Living conditions on board
- Extremely limited living space: each sailor has a 60-centimeter-wide bunk
- Work schedule based on watches: 6 hours on watch, 12 hours of rest, in continuous rotation
- Complete absence of natural light throughout the patrol
- Communication with the outside world is very limited and filtered for security reasons
- Careful catering: food quality is a key factor in crew morale
- A military watch is essential for managing watches
The profile of submarine sailors
Becoming a submariner in the French Navy involves rigorous psychological and physical selection, several months of specialized training at the Brest Submarine School, and signing a specific voluntary service commitment. In return, submariners receive a significant hazard bonus and special consideration within the armed forces.
FAQ: The most frequently asked questions about military submarines
What is the maximum depth of a military submarine?
The maximum operational depth of military submarines is classified as a defense secret. However, it is estimated that modern SSBNs and SSNs can dive between 300 and 400 meters . The absolute historical record is held by the Soviet experimental submarine K-278 Komsomolets, which reached 1,027 meters in 1985—a feat that has not been repeated since.
How long can a submarine remain submerged?
A nuclear-powered submarine can theoretically remain submerged indefinitely, thanks to its nuclear reactor, which generates electricity and continuously regenerates the air. In practice, the limitation is human: food supplies and the crews’ psychological endurance set the maximum patrol duration at 70–90 days for French SSBNs.
Which countries have nuclear-powered submarines?
Only six countries countries worldwide can operate nuclear-powered submarines: the United States, Russia, France, the United Kingdom, China, and India. France is the only European Union country with this capability, giving it a unique strategic status on the continent.
Conclusion
The military submarine is much more than a weapon: it is a symbol of national sovereignty, a concentration of cutting-edge technology, and the setting for an extraordinary life for exceptional sailors. With its 4 SSBNs and next-generation SSNs, France is one of the few nations in the world to have mastered this technology fully, from start to finish—from design by Naval Group to operation by the French Navy.
Passionate about the military and naval world? Discover our selection of tactical equipment at Surplus Militaires France: military spotting scopes for observation and robust military watches for all environments.
→ Discover our military spotting scopes | → Explore our military watches