Invisible highways: the vast network of undersea cables that power our connectivity

Sharing data in the blink of an eye has become a given in much of the world, and yet we rarely stop to think about what makes it possible: a complex global network of cables deep under the ocean that silently connects us.

In the modern information age, undersea cables have become a solid foundation for digital connectivity, Tomas Lamanauskas, Deputy Secretary-General of the International Telecommunication Union (ITU), told UN News ahead of a global summit on the topic starting in Portugal on Monday.

Through it, trillions of dollars in transactions occur in the global economy and continuous access to information.

“Approximately 99 percent of international Internet traffic passes through submarine cables. Even the conversation that you and I are having now is transmitted through these cables,” he said.

“People know about visible access points such as mobile networks, satellites and fixed Internet, but the underlying infrastructure that supports them is the vast network of undersea cables – our digital highways.”

These invisible highways, made up of fiber optic cables connecting landing points, are laid hundreds of meters below the ocean surface by ships laying cables.

Mr. Lamanauskas stressed that as our dependence on digital connectivity continues to grow, strengthening the resilience of these cables and developing collective strategies has become increasingly important.

This will be a key theme of the Second International Submarine Cable Resilience Summit, taking place on Monday and Tuesday in Porto, Portugal.

Fast data transmission

Connecting different parts of the world through communication cables is not a new idea. In 1850, England and France were linked for the first time by an underwater telegraph cable.

Since then, technology has constantly evolved, from telegraph services to telephone networks and now to high-speed Internet over fiber optic cables. Today, hundreds of terabits of data pass per second through these cables strung along the seafloor.

Around the world, there are more than 500 commercial undersea cables linking continents, markets and homes.

Relatively thin and about the width of a garden hose, these cables stretch for about 1.7 million kilometers, long enough to circle the Earth several times.

To lay them, the seabed is inspected to find routes with fewer risks and less impact on the environment. Special ships then unroll large spools of fiber optic cable on the ocean floor.

Disruption of cable traffic

As these cables increasingly form the backbone of the global economy, any interruption in the flow of data can be instantly noticed and affect the economic activities, technological and emergency services, security systems and Internet access of billions of people around the world.

Typically between 150 and 200 cable incidents occur each year.with an average of three to four per week.

The senior ITU official recalled that “in recent years, there have been quite a few high-profile incidents, from the Red Sea to West and East Africa.

“For example, in 2024, incidents with undersea cables in the Red Sea disrupted approximately 25 percent of data traffic between Europe and Asia.”

Outages in cable connectivity can be caused by earthquakes, underwater landslides and volcanic eruptions. However, statistics show that around 80 percent of incidents are caused by human activity, whether ships’ anchors or fishing trawlers damage cables.

Every millisecond matters

Lamanauskas cited the example of Tonga, which has experienced three major disruptions since 2019, caused by an earthquake, volcanic eruptions and inadequate anchoring. Due to the lack of a diverse network in remote regions, when a cable is cut, a vast territory can be offline.

“Imagine you and your entire community are offline for a week.without being able to access essential services such as digital healthcare, access to information and education.”

“Imagine the impact on New York stockbrokers if even a millisecond delay occurred due to cable congestion or an incident with an undersea cable. Every moment matters.”

Repairing the invisible roads

Aside from natural wear and tear, “some of the cable infrastructure laid during the dot-com boom of the 2000s is now reaching maturity, as these cables were designed for an average lifespan of 25 years,” he added.

DSG Lamanauskas explained that, in the event of an incident, engineers usually quickly identify the affected area and “The repair work itself is not always the most complicated part. What is usually more complex is obtaining all the necessary permits and licenses.especially when multiple or overlapping jurisdictions are involved.”

Depending on the location and extent of the damage, the call to cable vessels and repair work can take days, weeks or months. In busy places, these boats are usually close by, but reaching remote areas can take longer. In many countries, the lack of a clear focal point to manage these operational requirements compounds the challenge.

Lamanauskas noted that laying new cables is typically a multi-year project that requires a considerable amount of time. “It requires extensive planning and is also typically expensive. While shorter cables cost millions, longer ones can cost hundreds of millions.”

What is the ITU doing?

As the United Nations agency for digital technologies, ITU works to improve the resilience of global undersea cables through collaboration, standard setting and technical guidance. Its priorities include developing resilient measures, streamlining maintenance and repair processes and adopting more sustainable practices.

“Over the last 40 years, the capacity of these optical cables has increased 40 percent annually. It is exponential growth which in turn drives the exponential growth of the Internet,” added Mr. Lamanauskas.

Mr. Lamanauskas clarified that the ITU is not an operational body and does not repair cables.

“Instead, we focused on creating the right enabling environment by shortening permitting timelines, establishing clear points of contact, raising awareness to prevent accidental damage and facilitating faster repairs.”

As demand for connectivity and data increases at unprecedented speed, these efforts will play a key role in strengthening the foundation for shared progress and shaping the future of the global digital landscape.