October 25, 2021

I, Science

The science magazine of Imperial College

Guest writer Miles Murray shows us the ropes in how underwater cables provide our internet.

Miles Murray
30th April 2021

Few people realize just how much the world still relies on wires for everyday communication. Texts are sent through WiFi and most work today is done via the cloud—it’s easy to forget that wires are still essential to transmit all of these communications to other people and across the globe.

Underwater cables are thenerve center of the entire internet and crucial to global communication. With over 750,000 miles of cables running along the Earth’s seabed, they’re responsible for carrying more than 95 percent of the world’s daily communications. Without them, entire continents would be digitally disconnected.

Since these underwater cables are so important to the internet, you’d think they would be more protected, right? Turns out, the vast majority of the miles and miles of cables are simply sitting on the bottom of the ocean. Anyone with a boat and some cable cutters could disrupt digital communication for millions of people—which has actually happened. Here are four problems underwater cables can—and often do—face that can put the world’s internet connection in jeopardy.

What Are Underwater Internet Cables?

Underwater internet cables are thin fiber optic cables that are placed on the seafloor that connects everyone around the world to the internet and allow for transoceanic communication. The first transatlantic telegraph cable became operational back in 1850, and even though technology has advanced leaps and bounds since, we’re still extremely dependent on these vulnerable cables.

The cables themselves are thinner and more vulnerable than you’d think. Traditional cables like wire rope are made to withstand almost massive amounts of strain and wear and tear—underwater cables are not. They’re around the size and thickness of an everyday garden hose. Depending on where the cables will be placed on the seafloor, other materials like plastic, steel, and tar are added to protect them from the often dangerous ocean environment, but simple bolt cutters could still cut through them like butter.

Threat 1: Boat Anchors

Since these cables are simply placed on the seabed, boat anchors often catch on the wires and slice right through them. In 2016, three cables in the English Channel were accidentally cut by boat anchors; it took three weeks for the cables to be fixed. And in 2008, a cut cable from a poorly dropped anchor in Dubai left 75 million people without internet access. It’s a common enough accident that warning boats are often placed along key cable routes—but even then, there aren’t enough boats to guard every line.

Threat 2: Natural Disasters

Natural disasters can spell disaster for an entire country’s internet and communication infrastructure. While large companies like Amazon, Google, and Facebook spread their data across multiple wire routes in case of accidental failures, most companies can’t plan for outages from natural disasters. In 2011, a duel earthquake and tsunami severely damaged undersea cables across Japan, cutting off communication across the country and making relief efforts near impossible. It took months for services to be fully restored.

Threat 3: Accidents

While big companies have baked redundancies into their wire communications, some areas are more reliant on single wires to supply the internet to everyone. In 2011, an elderly Georgian woman accidentally sliced through a fiber cable while she was scavenging for copper to sell as scrap metal. This accident cut off the internet to all of Armenia. And since Georgia provides around 90 percent of Armenia’s internet, more than 3 million people were cut off from internet access.

Threat 4: Sabotage

Since the large majority of these cables go unmonitored, it wouldn’t take a lot to tamper with the thin undersea cables and cut off communication for millions of people. Five undersea cables were cut back in 2008, causing massive power outages across the Middle East and Asia. Many people believe that those cables were deliberately sabotaged since Israel and Iraq were not affected by the outages. Since limiting internet access and forced communications blackouts is a common tactic for governments in unstable regions to use, sabotaging vulnerable underwater lines is an easy way to quickly gain control of unfavorable situations.


Miles is Seattle based tech columnist and blogger. In his spare time, he has loved freelance writing for various science publications, exploring topics from outer space to emerging tech