When we send a message, watch a video, or browse a website, we rarely think about how the data gets from one place to another. Many people believe that the internet is powered mostly by satellites or wireless signals. While satellites do help, the truth is that undersea cables carry more than 95% of global internet traffic. These cables are the hidden highways of the internet—and they’re essential to our connected world.
What Are Undersea Cables?
Undersea cables, also known as submarine cables, are long, fiber-optic wires that lie on the ocean floor. They connect countries and continents by transmitting data through light signals at incredible speeds. These cables can stretch thousands of miles under oceans and seas, linking major internet hubs around the globe.
For example, when you video call someone in Europe from the U.S., your voice and image likely travel through one of these cables across the Atlantic Ocean.
A Brief History
The idea of undersea communication isn’t new. The first successful transatlantic cable was laid in 1858, but it was used for telegraphs, not internet. That cable sent short messages using electrical signals. Over time, technology improved, and undersea cables began to carry telephone conversations in the 20th century.
By the late 1980s and early 1990s, fiber-optic cables replaced older systems. These cables use light instead of electricity and can carry massive amounts of data at once. Today, we rely on them for everything from banking and business to social media and online gaming.
How Do They Work?
Undersea cables are made up of bundles of fiber-optic strands—very thin threads of glass or plastic. Each strand carries data as pulses of light, which move extremely fast.
To protect these fragile fibers, the cables are wrapped in several layers, including waterproofing, steel armor, and insulation. Despite the strong build, the cables are only about the thickness of a garden hose.
The cables are laid by special ships that carefully drop them to the ocean floor, often across thousands of kilometers. In shallow waters, the cables are sometimes buried beneath the seabed to protect them from anchors or fishing equipment.
Why Are They So Important?
Undersea cables are the backbone of the internet. They carry information between countries far faster and more reliably than satellites. That includes:
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Emails and chats
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Streaming video and music
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Online payments and banking
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Cloud storage and business data
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International phone and video calls
Because these cables offer such high capacity and low delay, companies like Google, Facebook, Amazon, and Microsoft have invested heavily in them. Some even build and own their own cable networks to ensure faster, more secure service.
Where Are These Cables?
There are over 500 undersea cables around the world, with a combined length of more than 1.3 million kilometers. Major cables cross the Atlantic Ocean, Pacific Ocean, Indian Ocean, and the Mediterranean Sea. Some connect remote islands to the global internet.
You can view real-time maps of undersea cables on websites like SubmarineCableMap.com, which shows how the world is connected under the waves.
Are They Safe?
Undersea cables are built to last and are very durable. But they’re not completely safe. They can be damaged by:
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Fishing trawlers or ship anchors
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Earthquakes or undersea landslides
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Sabotage or spying (rare but possible)
When a cable is damaged, repair ships are sent out to lift it from the seabed and fix or replace the broken part. This process can take days or even weeks, depending on the location and weather.
To prevent interruptions, data is often rerouted through other cables while repairs are made.
The Future of Undersea Cables
As the world demands faster internet and more data, new cables are constantly being planned and laid. Some of the latest ones promise super-fast speeds and low-latency connections, especially for gaming, finance, and global communication.
In the future, we may also see better protection technologies, smarter routing systems, and increased capacity to support things like 8K video, remote work, and the growing Internet of Things (IoT).
Final Thoughts
Undersea cables may be out of sight, but they are always working hard beneath the ocean. They form the quiet, powerful network that keeps the modern world connected—from business to entertainment to personal communication.
Next time you send a message across the world or stream your favorite show, remember that your data likely traveled through one of these invisible, underwater highways—connecting continents one light beam at a time.
