• When Browsing Online, Thank the Undersea Cables
    01st May 2023

    When Browsing Online, Thank the Undersea Cables

Did you know that 99% of international data is transmitted through subsea cables? These underwater cables span thousands of miles across the ocean floor to carry telecommunications and internet signals.

Subsea or submarine cables are fiber optic cables laid on the ocean floor to transmit data between continents. The backbone of telecommunications networks, these cables transmit data world-wide at high speeds. As critical providers of global internet connectivity, they play a key role in enabling trade, finance and instant communication across international borders.

In this article, we’ve listed some interesting facts about subsea cables sure to leave you amazed.

The first subsea cable

The first transatlantic submarine cable was laid in 1858 and took two years to complete. Unfortunately, the cable failed after only a few weeks due to impaired insulation resistance, creating short circuits.

Special laying ships

Subsea cables are laid on the ocean floor using specialized cable-laying ships, which carefully lower the cable onto the seabed. The cables are typically buried beneath the seabed to protect them from damage caused by ship anchors and fishing trawlers. The name of the first ship that laid the Atlantic Telegraph cable in 1858 was HMS Agamemnon across the Atlantic Ocean.

Global connectivity

Nearly 99.9% of the world’s intercontinental electronic communications traffic is carried by the undersea cable infrastructure. Without the subsea cables, our continents would’ve been isolated without terrestrial connectivity.

Life span

Submarine cables are generally designed with a lifespan of around 25 years, after which they may need to be replaced or upgraded to maintain performance and reliability. Typically made of several layers including copper or aluminium conductors, fiber optic strands, insulation materials, and an outer polyethylene sheath, the subsea cables are encased in a protective coating to withstand underwater environments and safeguard them from damage.

Longest subsea cable

The world’s longest submarine cable is the SEA-ME-WE 3 (South-East Asia, Middle East, Western Europe 3), which spans 39,000 kilometres (24,233 miles) and connects 33 countries. Incredibly, this is equivalent to about one-tenth of the distance from the Earth to the Moon.

Speedy transmissions

Submarine cables can transmit data at speeds of up to 20 terabits per second (Tbps) over a single fiber pair, which is equivalent to transmitting 10 million high-definition videos simultaneously. This is made possible using dense wavelength division multiplexing (DWDM) technology, which allows multiple wavelengths of light to be transmitted over a single fiber optic strand as thin as the human hair.


Submarine cables are vulnerable to several threats, including natural disasters such as earthquakes and undersea landslides. Human activities such as anchoring and fishing activities account for approximately ¾ of all submarine cable glitches. Also interestingly, predator sharks have been biting down on fiber optic cables under the Pacific, possibly confused by electrical signals that resemble fish.

Repairs no ordinary job

Repairs to submarine cables are challenging and expensive, often requiring specialized equipment and skilled divers to carry out repairs several thousand meters down the oceanic floor. Also equally intriguing is that the cost of laying a new submarine cable can range from tens to hundreds of millions of dollars, depending on the distance, depth, and complexity of the project.

Next time whenever you’re browsing the internet for videos or news, don’t forget to thank the incredible network of undersea cables.

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