The secret of fiber optic cables hidden under the ocean

552 cable lines thousands of kilometers long across the sea are responsible for transmitting images and sounds from programs and matches that users cannot attend directly.

Although satellite connections are increasingly talked about, undersea cables are still the main means of global communication and commerce. The undersea fiber optic cable system provides more than 99% of Internet connection traffic between continents. TeleGeography, a company that tracks fiber optic cable business activities, said that there are currently 552 ocean-going cable routes worldwide, with many more routes still being planned to operate.

Fiber optic cable under the ocean. Illustration: Cnet

Technology giants such as Meta, Microsoft, Amazon and Google are not only the gatekeepers of the Internet but also operate the Internet's neural network by holding a transatlantic cable system called Amitié, which can transmit downloads 400 terabits of data per second, 400,000 times faster than home broadband. It is estimated that the cost of installing a transatlantic cable is about 250-300 million USD.

From rope production to fiber optic cable business

The most famous undersea fiber optic cable factory today is SubCom. This company has been on the market since the 1800s, starting with the production of rope. SubCom CEO David Coughlan said: "At that time most rope was used in the shipping industry. A deep-water port factory with the ability to get out to sea quickly and experience in winding rope was all that was needed. necessary for a rope company to switch to fiber optic cable."

Today, high-speed cables can transmit an average of 250 terabits of data per second. However, the underlying technology of this connection is still used since the 1800s. Engineer Werner Siemens and scientists have found a way to lay electric cables under rivers, across the English Channel and the Mediterranean Sea.

Initially, many fiber optic cables could not withstand the pressure and were torn apart. The first transatlantic cable project went into operation in 1858. At that time, the cable transmitted just over one word per minute and quickly failed.

Later, scientists discovered that high purity copper could improve signal transmission, stronger shielding could help reduce cable breaks, and repeaters installed periodically along the cable increased Signal enhancement and polyethylene insulation replace the previous rubber-like material that can be harvested from a plant called gutta-percha.

These inventions created the first major turning point in the cable industry. Phone calls appeared, replacing telegraph messages. A transatlantic cable installed in 1973 could handle 1,800 conversations at once. In 1988, AT&T installed the first transatlantic cable using glass fiber instead of copper wire. This improvement increases the number of concurrent calls to 40,000.

What is the most afraid of undersea fiber optic cables?

Not sharks or natural disasters, the most feared undersea fiber optic cables are human impacts. It is designed to prevent saltwater corrosion, but cannot withstand human damage. Vessels are one of the main risks for cables to break, especially where there is a high density of moored vessels.

The cable laying vessel contained hundreds of miles of cable coiled up inside three tanks.  Note the scale showing that this tank is 7 meters (22 feet) deep.  This shows a section of the Merea cable built by Microsoft and Facebook's parent company Meta.  Microsoft
A roll of fiber optic cable invested by Microsoft and Meta is placed in a specialized ship to be taken to the ocean. Photo: Microsoft

TeleGeography said installing underground cables is extremely difficult. However, about every three days a line is cut. The main culprits, accounting for 85% of cable breaks, are fishing equipment and anchored boats. Ships often drop anchor to weather the storm, but the storm pushes the boat to move continuously, causing the iron anchor on the seabed to also be displaced and hit the fiber optic cable.

Frank Rey, leader of Microsoft's superfast networking system, said most cable breaks occur in shallow water areas, near land. There, the cable is covered in metal "armour" but is still not safe enough from impacts from fishing boats.

Other impacts that cause fiber optic cables to fail are earthquakes and landslides. Human-caused climate change is creating more extreme storms.

Cable operators can pinpoint the exact location of a broken cable, but repair ships often have to wait for a government permit to make repairs. Rey said the average error requires two to four weeks to fix.

Fiber optic cable - the target of military attacks

Not simply an Internet transmission tool, in many cases fiber optic cables are also within the reach of armed attacks. British Prime Minister Rishi Sunak once said that undersea fiber optic cables are indispensable but they have never been safe.

In a 2021 report, CNAS, a bipartisan US national security think tank, also concluded that undersea cables are vulnerable to military attacks. "Fiber-optic cable incidents can cause strategists, governments to lose focus, and even make mistaken decisions due to having to respond to sudden loss of Internet connection," Chris Dougherty, senior member of CNAS , stated in the report.

Many countries understand that the potential role of submarine cables in the ocean is much larger than the normal connection task. It may even turn into a new front.

Underground network on the ocean floor

Due to the importance and vulnerable characteristics of undersea cables, a race for Internet transmission autonomy is not only taking place at the scale of technology corporations but is also a strategy of many countries. When a storm hits the Atlantic Ocean, most of the fiber optic cables crossing this sea will be affected. Operators should never keep all their eggs in one basket and often reserve multiple routes. In case a certain line fails, another line will be brought in to rescue.

Branching technology is also becoming a suitable answer for the different geographical conditions of each region. Instead of running a cable from one end to the other, scientists have found a solution that allows fiber optic cables to branch in many countries.

The new Sea-Me-We 6 route from France to Singapore is designed to connect with 17 other countries. A number of new routes are also being built to connect Europe, Africa, the Middle East, Asia, the Americas and many island countries, allowing for a network of submarine cables according to a widespread branching scheme under the ocean.

Another secret of fiber optic cable is that it can transmit the Internet through air ducts instead of glass fibers. In December 2022, Microsoft acquired Lumenisity - a company developing hollow fibers with a small air tube in the middle. The speed of light in air is 47% faster than in glass, reducing latency, which is a key limitation of network performance.