SUMMARY
Most international internet traffic does not travel through satellites. It moves through thousands of kilometres of fibre-optic cables laid across the world's oceans. These largely invisible cables connect continents, carry enormous amounts of data and form one of the most important pieces of infrastructure behind modern communications, cloud computing, financial markets and artificial intelligence.
TECHNOLOGY — Every time someone sends a message across the world, watches a video hosted on another continent or accesses a website stored in a distant data centre, the information may be travelling through a network that most people never see.
Far beneath the ocean's surface, fibre-optic cables connect countries and continents, carrying huge volumes of digital information between data centres, telecommunications networks and internet users.
These cables are among the least visible but most important components of the global internet.
What Are Undersea Internet Cables?
Undersea internet cables, also called submarine communications cables, are long fibre-optic cables installed on the seabed to connect different parts of the world.
Inside the cable are optical fibres that transmit information as pulses of light.
Instead of sending data as electrical signals across copper wires for thousands of kilometres, modern submarine cables use light travelling through extremely thin strands of glass.
This allows enormous quantities of information to move rapidly between continents.
How Much of the Internet Travels Through Cables?
It is easy to imagine that international internet traffic mainly travels through satellites because satellites are visible and receive so much attention.
The reality is very different.
Submarine cables carry the overwhelming majority of intercontinental telecommunications traffic. They provide the high-capacity connections required for modern internet services, cloud platforms, financial systems and international communications.
Satellites remain extremely important, particularly for remote areas, ships, aircraft and locations where terrestrial infrastructure is difficult to build. But for the huge volumes of data moving between major population centres, fibre-optic cables are generally more efficient.
Why Fibre Optics?
Fibre-optic technology is based on a simple but powerful idea: information can be transmitted using light.
A transmitter converts digital information into optical signals. Those signals travel through the fibre before being converted back into electrical data at the receiving end.
Because light can carry enormous amounts of information, fibre-optic systems can support the massive data volumes generated by modern internet services.
This is particularly important as video streaming, cloud computing, artificial intelligence and other data-intensive technologies continue to expand.
What Does a Submarine Cable Look Like?
A submarine cable is much more sophisticated than a simple fibre-optic wire.
The optical fibres are protected by multiple layers designed to withstand the harsh conditions of the ocean environment.
Depending on where the cable is being installed, its construction can include protective materials designed to resist pressure, water penetration and physical damage.
Cables used in shallow waters may receive additional armouring because they are more exposed to anchors, fishing equipment and other human activities.
In deeper parts of the ocean, cables can be lighter because they generally face fewer physical hazards.
How Does Data Travel Across an Ocean?
Imagine sending a message from Lagos to someone in London.
Your phone first sends the data through a local network. From there, it may travel through terrestrial fibre infrastructure before reaching a cable landing station.
The information is then converted into optical signals and transmitted through a submarine cable crossing the Atlantic.
When the signal reaches the other side, it enters another landing station and continues through terrestrial networks until it reaches its destination.
The entire process can happen in fractions of a second.
What Is a Cable Landing Station?
A cable landing station is the facility where a submarine cable connects to terrestrial telecommunications infrastructure.
These facilities act as gateways between the undersea network and networks on land.
They contain equipment that manages optical signals, connects the submarine cable to other networks and helps operators monitor the cable's performance.
Because landing stations connect international cables to national networks, they can be strategically important pieces of telecommunications infrastructure.
How Do Cables Receive Power?
Although information travels through the cable as light, the system also requires electrical power.
Submarine cables contain equipment called repeaters at intervals along their length.
These devices amplify or regenerate optical signals so that information can travel thousands of kilometres without becoming too weak.
Electrical power is supplied through conductors within the cable to operate this equipment.
Why Do Signals Need Repeaters?
Light travelling through optical fibre gradually loses strength.
If a signal travelled thousands of kilometres without assistance, it would eventually become too weak to reliably interpret.
Repeaters positioned along the cable help overcome this limitation.
Modern submarine cable systems can therefore carry signals across entire oceans while maintaining high data transmission performance.
How Are Undersea Cables Installed?
Installing a submarine cable is a major engineering operation.
Before a cable is laid, specialists survey the proposed route to identify suitable areas on the seabed.
They examine factors such as water depth, geological conditions and potential hazards.
A specialised cable-laying ship then carries the cable and carefully releases it onto the seabed.
In shallow and vulnerable areas, equipment can bury the cable beneath the seabed to provide additional protection.
What Happens When a Cable Breaks?
Submarine cables can be damaged for several reasons.
Fishing equipment and ship anchors are among the most common causes of damage in some areas.
Natural events such as underwater landslides and earthquakes can also disrupt cables.
When a cable fails, internet traffic does not necessarily stop completely.
Modern networks are designed with multiple routes, allowing traffic to be redirected through other cables where capacity is available.
However, if several cables serving the same region are damaged at the same time, the consequences can become much more serious.
Why Cable Redundancy Matters
Internet infrastructure relies heavily on redundancy.
Having several submarine cables connecting different regions means network operators can reroute traffic when one connection becomes unavailable.
This is one reason countries and technology companies continue to invest in additional submarine cable routes.
More routes can mean greater capacity as well as greater resilience.
Why Undersea Cables Matter for Africa
Africa has become increasingly connected to the global submarine cable network.
Multiple systems now connect African coastal countries to Europe, the Middle East and Asia.
For countries such as Nigeria, international submarine cables are particularly important because they provide connections to global cloud platforms, content networks and international businesses.
Greater submarine cable capacity can support faster internet services and help data centres and digital businesses connect to international networks.
However, the existence of cables does not automatically guarantee affordable or reliable internet access. Terrestrial infrastructure, electricity, network investment and competition among service providers also matter.
Why Technology Companies Build Cables
Submarine cables were once primarily associated with telecommunications companies and international carriers.
That has changed.
Large technology companies now have major interests in submarine cable infrastructure because their businesses depend on enormous amounts of global data traffic.
Cloud computing, video platforms, search engines, artificial intelligence services and social networks all require reliable international connectivity.
Owning or investing in cable capacity can give technology companies greater control over network capacity, performance and resilience.
Undersea Cables and Artificial Intelligence
The growth of artificial intelligence is increasing the importance of international data infrastructure.
AI systems rely on enormous data centres that exchange information with other facilities and users around the world.
Training large AI models can involve moving huge datasets between computing facilities.
AI applications also require users to communicate with remote computing infrastructure for tasks such as inference, data processing and content generation.
As these workloads grow, reliable high-capacity international networks become increasingly important.
Are Undersea Cables Vulnerable?
Yes.
The cables are physically protected, but they cannot be made completely immune to damage.
The seabed is a difficult environment, and cables can pass through areas where human activity or natural events pose risks.
Some routes are also strategically important because they connect regions with relatively few alternative pathways.
That creates concerns about resilience, particularly when several cables serving the same area are disrupted.
Can Undersea Cables Be Deliberately Damaged?
Technically, submarine cables can be damaged deliberately as well as accidentally.
This has raised growing concerns among governments because international communications infrastructure can have strategic importance.
However, proving deliberate interference can be difficult, particularly in deep water.
The security of submarine cables has therefore become an increasingly important issue in discussions about national resilience and critical infrastructure.
Who Owns the World's Undersea Cables?
Ownership varies from one cable system to another.
Telecommunications operators, governments, technology companies, infrastructure investors and consortiums of multiple companies can all participate in submarine cable projects.
A single cable may therefore have several owners or investors sharing its capacity.
This model allows the enormous cost of building and operating a cable system to be distributed among multiple participants.
How Expensive Are Submarine Cables?
Building a major submarine cable can cost hundreds of millions of dollars depending on its length, capacity, technology and route.
The total investment includes cable manufacturing, surveying, specialised ships, landing stations, network equipment and long-term maintenance.
Despite the high upfront cost, the enormous capacity of fibre-optic cables can make them highly valuable infrastructure for international communications.
Why the Internet Cannot Simply Depend on Satellites
Satellites have important advantages, particularly when connecting locations that lack terrestrial infrastructure.
However, submarine fibre-optic cables have major advantages for massive intercontinental data flows.
Fibre networks can provide extremely high capacity and relatively low latency over long distances.
That makes them especially suitable for connecting major data centres and densely populated regions.
The future internet will therefore likely continue to use both systems rather than replacing one with the other.
The Future of Submarine Cables
The demand for international connectivity is unlikely to disappear.
More cloud services, streaming platforms, connected devices, AI systems and digital businesses will require more data to move between continents.
This is driving investment in new cable systems with greater capacity and more diverse routes.
New technologies are also being developed to increase how much information can be transmitted through existing fibre infrastructure.
Why This Infrastructure Matters More Than People Realise
The most striking thing about submarine cables is how invisible they are.
People interact with the internet through phones, laptops and applications. The physical infrastructure underneath those services is rarely visible.
Yet without international fibre connections, much of the modern digital economy would struggle to function.
Financial transactions, international business communications, cloud applications, social networks, video services and AI workloads all depend on networks capable of moving information rapidly across borders.
Conclusion
Undersea cables are the hidden infrastructure connecting the world's digital economies.
Thousands of kilometres of fibre-optic cable lie across ocean floors, carrying enormous volumes of information between continents every second.
They support everything from ordinary internet browsing and video calls to financial markets, cloud computing, telecommunications and artificial intelligence.
The systems are not indestructible, which is why network redundancy, route diversity and maintenance are so important. As global dependence on digital infrastructure increases, protecting and expanding submarine cable networks will become increasingly important.
The next time you send a message across the world or access information stored on another continent, there is a good chance your data is taking a journey beneath the ocean. The global internet may feel wireless, but much of its most important infrastructure is hidden deep beneath the sea.
