"There's a lot of talk these days about how space is the next contested domain. But I think undersea is going to be very much a contested domain," said Steve Bowsher, president of In-Q-Tel, a CIA-backed nonprofit that invests in startups on behalf of the CIA, FBI, NSA and other US government agencies.

"Those are going to be targets in any sort of kinetic conflict."

The Secret Life of the 500+ Cables That Run the Internet

Laced across the cold depths of the world's oceans is a network of multimillion-dollar cables, which have become the vital connections of our online lives.

Stephen Shanklandprincipal writer

Stephen Shankland has been a reporter at CNET since 1998 and writes about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.

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I've been covering the technology industry for 24 years and was a science writer for five years before that. I've got deep expertise in microprocessors, digital photography, computer hardware and software, internet standards, web technology, and other dee

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Stephen Shankland

Aug. 6, 2023 5:00 a.m. PT

Though satellite links are becoming more important with orbiting systems like SpaceX's Starlink, subsea cables are the workhorses of global commerce and communications, carrying more than 99% of traffic between continents. TeleGeography, an analyst firm that tracks the business, knows of 552 existing and planned subsea cables, and more are on the way as the internet spreads to every part of the globe and every corner of our lives.
You probably know that tech giants like Meta, Microsoft, Amazon and Google run the brains of the internet. They're called "hyperscalers" for operating hundreds of data centers packed with millions of servers. You might not know that they also increasingly run the internet's nervous system, too.

Zooey Liao/CNET

The Secret Life of the 500+ Cables That Run the Internet

Laced across the cold depths of the world's oceans is a network of multimillion-dollar cables, which have become the vital connections of our online lives.

The concert is in London. You're watching it live from your home in Atlanta. What makes that possible is a network of subsea cables draped across the cold, dark contours of the ocean floor, transmitting sights and sounds at the speed of light through strands of glass fiber as thin as your hair but thousands of miles long.

These cables, only about as thick as a garden hose, are high-tech marvels. The fastest, the newly completed transatlantic cable called Amitié and funded by Microsoft, Meta and others, can carry 400 terabits of data per second. That's 400,000 times faster than your home broadband if you're lucky enough to have high-end gigabit service.

And yet subsea cables are low-tech, too, coated in tar and unspooled by ships employing basically the same process used in the 1850s to lay the first transatlantic telegraph cable. SubCom, a subsea-cable maker based in New Jersey, evolved from a rope manufacturer with a factory next to a deep-water port for easy loading onto ships.

. . .TeleGeography, which tracks subsea cables closely, projects $10 billion will be spent on new subsea cables from 2023 to 2025 around the world.

Google-owned cables already built include Curie, Dunant, Equiano, Firmina and Grace Hopper, and two transpacific cables are coming, too: Topaz this year and, with AT&T and other partners, TPU in 2025.

Such cables don't come cheap: A transatlantic cable costs about $250 million to $300 million to install, Mauldin said.
The cables are critical. If one Azure region fails, data centers in another region come online to ensure customers' data and services keep humming.

In the US and Europe, terrestrial cables shoulder most of the load, but in Southeast Asia, subsea cables dominate, Rey said.

With the hyperscalers in charge, pushing data instead of voice calls, subsea networks had to become much more reliable. It might be a minor irritation to get a busy signal or dropped call, but interruptions to computer services are much more disruptive. "If that drops, you lose your mind," Coughlan said. "The networks we make today are dramatically better than what we made 10 years ago."

GeoGarage blog

GeoGarage blog: The secret life of the 500+ cables that run the Internet

The number of subsea internet cables has surged. By 2025, a total of 552 should be operational.

Data: TeleGeography; graphic: Viva Tung/CNET

The origin story of subsea communications

Today's cables send up to 250 terabits per second of data, but their technology dates back to the 1800s when scientists and engineers like Werner Siemens figured out how to lay telegraph cables under rivers, the English Channel and the Mediterranean Sea. Many of the early cables failed, in part because the weight of a cable being laid on the bottom of the ocean would rip the cable in two. The first transatlantic cable project that succeeded operated for only three months in 1858 before failing and could only send just over one word per minute.
But investors eager to cash in on rapid communications underwrote the development of better technology. Higher copper purity improved signal transmission, stronger sheathing reduced cable breaks, repeaters installed periodically along the cable boosted signal strength and polyethylene insulation replaced the earlier rubberlike material harvested from gutta-percha trees.
Telephone calls eventually replaced telegraph messages, pushing technology further.

A transatlantic cable installed in 1973 could handle 1,800 simultaneous conversations.
In 1988, AT&T installed the first transatlantic cable to use glass fiber optic strands instead of copper wires, an innovation that boosted capacity to 40,000 simultaneous phone calls.

A subsea internet cable, sliced to show a cross section of its fiber optic lines for data transfer, steel cabling for strength, copper for power distribution and plastic for insulation and protection. — A subsea internet cable from manufacturer SubCom shows, from the center outward, its optical fibers for data transfer, steel cabling for strength, copper for power distribution and plastic for electrical insulation and protection.
Stephen Shankland/CNET

SubCom's subsea cable factory dates back to its rope-making roots in the 1800s. "Most rope in that time was used on ships or needed to be transported by ships," CEO Coughlan said. "A factory on a deep port, with quick access to the ocean and with winding capabilities, is what was needed to transform into the telephone cable business."

..."The whole network of undersea cables is the lifeblood of the economy," said Alan Mauldin, an analyst with TeleGeography. "It's how we're sending emails and phone calls and YouTube videos and financial transactions."

Two thirds of traffic comes from the hyperscalers, according to Telegeography. And the data demands of hyperscalers' subsea cable is surging 45% to 60% per year, said SubCom Chief Executive David Coughlan. "Their underlying growth is fairly spectacular," he said.

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Hyperscalers' data demands are driven not just by their own content needs, like Instagram photos and YouTube videos viewed around the world. These companies also often operate the cloud computing businesses, like Amazon Web Services and Microsoft Azure, that underlie millions of businesses' global operations.

"As the world's hunger for content continues to increase, you need to have the infrastructure in place to be able to serve that," said Brian Quigley, who oversees Google's subsea and terrestrial networks.