How are submarine cables deployed with top-tier reliability?

Overview 

Submarine cables are deployed reliably through continuous optical validation before, during, and after installation. Testing gives operators the confidence to launch service, localize faults, validate repairs, and protect network performance across the full subsea cable lifecycle.

Why do submarine cables matter to the global digital economy?

Submarine cables form the backbone of international connectivity. They carry over 99% of intercontinental data and more than $12 trillion in daily financial transactions.

There is no practical substitute at global scale. Satellites cannot match the capacity, latency, or cost efficiency of fiber-optic subsea systems. As AI, cloud, and hyperscale infrastructure accelerate data demand, submarine networks must be deployed, upgraded, and restored with exceptional reliability.

A system under constant threat 

Submarine networks operate in one of the harshest environments on earth. Cables stretch across thousands of kilometers, often lying unprotected on the ocean floor. Near shore, they are exposed to dense human activity. And once deployed, access is extremely limited. 

The result? Issues are not rare, they’re expected. According to TeleGeography, the global subsea network experiences around 200 faults per year—roughly four every week. The vast majority of these are caused by human activity such as fishing, anchoring, and dredging. 

In other words, subsea networks are not failure-free systems. They are systems that must detect, localize, and recover—reliably and repeatedly.

The real cost of getting it wrong 

When something goes wrong in a subsea network, the consequences are immediate and expensive. Repair operations require specialized vessels, complex logistics, and regulatory approvals. According to TeleGeography, repairs can cost up to $1 million per day, and the average delay before repair work even begins is approximately one and a half months, often due to permitting and coordination challenges. Even more critically, once a repair vessel is on-site, there is no room for error. Every additional intervention means more time, more cost, and more disruption. 

How to build confidence across the cable lifecycle? 

From initial deployment to long-term upgrades, subsea networks require continuous validation: 

• Before deployment, teams must prove the fiber is ready, because there is no fallback once it’s laid.   
• During commissioning, they must validate performance before traffic goes live, ensuring revenue can start without risk.   
• During maintenance, they must localize faults quickly and accurately, because delays are costly and service must be maintained.   
• After repair, they must confirm the work before the vessel leaves, because a second intervention is not an option.   
• During upgrades, they must ensure the network has the margin to support future capacity, especially as coherent technologies and higher speeds become the norm. 

At every stage, the value of testing is not simply the measurement itself. It’s the confidence it creates from top-tier reliability to move forward. 

Turning test measurements into decisions 

In an industry where billions are already invested in resilience, the challenge is about turning test data into trusted decisions. This is where the right test partner makes the whole difference. 

EXFO supports subsea stakeholders across the full cable lifecycle, from lab validation to deployment, commissioning, landing-station characterization, maintenance, repair validation, and upgrades.

By combining comprehensive optical testing—ranging from connector inspection, link characterization and fault localization, spectrum and dispersion analysis to high-speed and coherent link validation (100G to 800G+)—with rugged, compact solutions and deep fiber-optic expertise, EXFO helps crews: 

• Reduce uncertainty 
• Avoid costly mistakes 
• Accelerate decision-making 
• And ultimately, protect the business case of every operation

In an environment where every decision carries operational and financial consequences, confidence is the most valuable output of testing.