The invisible seafaring industry that keeps the internet afloat


OnOn the afternoon of March 11th, 2011, Mitsuyoshi Hirai, the chief engineer of the cable maintenance ship Ocean Link, was sitting in his cabin 20 miles off Japan’s eastern coast, completing the paperwork that comes at the end of every repair. Two weeks earlier, something — you rarely knew what — damaged the 13,000-mile fiber optic cable connecting Kitaibaraki, Japan, and Point Arena, California. Alarms went off; calls were made; and the next day, Hirai was sailing out of the port in Yokohama to fix it.

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The repair was now nearly done. All that remained was to rebury the cable on the seafloor, which they were doing using a bulldozer-sized remotely operated submersible named Marcas — and, of course, the paperwork. 

Suddenly, the ship began to shudder. Hirai got to his feet, found he could barely stand, and staggered out of his cabin, grasping the handrail as he pulled himself up the narrow stairway to the bridge. “Engine trouble?” Hirai asked the captain, who’d already checked and replied that everything seemed normal. The ship continued to tremble. Looking out from the bridge, the sea appeared to be boiling.

They turned on the television. An emergency alert showed that an earthquake had struck 130 miles northeast of their location. The shaking finally stopped, and in the silence, Hirai’s mind leapt to what would come next: a tsunami.

Hirai feared these waves more than most people. He had grown up hearing the story of how one afternoon in 1923, his aunt felt the ground shake, swept up her two-year-old brother, and sprinted uphill to the cemetery, narrowly escaping floods and fires that killed over 100,000 people. That child became Hirai’s father, so he owed his existence to his aunt’s quick thinking. Now, he found himself in the same position. He knew tsunamis become dangerous when all the water displaced by the quake reaches shallow water and slows and grows taller. The Ocean Link, floating in less than 500 feet of water, was too shallow for comfort.

A photo of Mitsuyoshi Hirai, the former chief engineer of the Ocean Link. He sits at a table, his hands folded on a chart.

In the family tree of professions, submarine cable work occupies a lonely branch somewhere between heavy construction and neurosurgery. It’s precision engineering on a shifting sea using heavy metal hooks and high-tension lines that, if they snap, can cut a person in half. In Hirai’s three decades with Kokusai Cable Ship Company (KCS), he had learned that every step must be followed, no matter how chaotic the situation. Above all else, he often said, “you must always be cool.” 

Across Ocean Link’s 400-foot deck, the ship’s 50 crew members were emerging from their cabins and workstations, trying to figure out what had just occurred. Over the intercom, the captain announced that there had been an earthquake, a tsunami was coming, and the crew should ready the ship to evacuate to deeper water. The crew fanned out to check fuel tanks and lash down machinery. Inside a darkened, monitor-filled shipping container on the starboard deck, the submersible’s pilot steered Marcas back toward the ship as fast as the bulky robot’s propellers could carry it. Minutes later, the submersible was hoisted aboard and the Ocean Link was underway.

The tsunami passed under them imperceptibly on their way out to sea, and when they came to a stop three hours later, the television was showing the first images of destruction. Members of the crew who weren’t working gathered on the bridge to watch the news, which continued to display a tsunami warning, a map of Japan with its eastern seaboard glowing red. They took turns trying to reach loved ones using the ship’s satellite phone, but no calls went through. 

As night fell, periodic aftershocks thumped against the hull. Hirai thought about his wife, who was working at a department store in Yokohama near the Ocean Link’s port; his son, a junior in high school at the time; and his parents, whom the family lived with in his hometown of Yokosuka — none of whom he’d been able to reach. Everyone had someone they were worried about.

But Hirai also began to think about the work he knew lay ahead. The Ocean Link was one of a small number of ships that maintain the subsea cables that carry 99 percent of the world’s data. Positioned in strategic locations around the planet, these ships stand ready to sail out and fix faults the moment they are detected, and most of the time, they are more than equal to the task. But earthquakes, Hirai knew from experience, were different. They didn’t just break one cable — they broke many, and badly. If what he feared had happened, Japan risked being cut off from the world in its moment of need.

Sure enough, that night, a call came from headquarters confirming the Ocean Link was safe and directing them to remain at sea until further notice, followed by messages announcing cable failure after cable failure, including the one they had just finished repairing.

Fumihide Kobayashi standing in front of the submersible Marcas.

Cable industry professionals tend to be pragmatic people, preoccupied with the material realities of working planet-scale construction. But in conversations about landing high-bandwidth cables in digitally neglected regions or putting millions of people back in contact with every fiber strand melted together, they often hint at a sense of larger purpose, an awareness that they are performing a function vital to a world that, if they do their jobs well, will continue to be unaware of their service.

For the Ocean Link crew, this awareness was bound up in a still unfolding national tragedy. They knew that whenever they returned to land, they would have to care for their loved ones quickly, because they would soon be going back out to sea. For how long, no one knew.

TheThe world’s emails, TikToks, classified memos, bank transfers, satellite surveillance, and FaceTime calls travel on cables that are about as thin as a garden hose. There are about 800,000 miles of these skinny tubes crisscrossing the Earth’s oceans, representing nearly 600 different systems, according to the industry tracking organization TeleGeography. The cables are buried near shore, but for the vast majority of their length, they just sit amid the gray ooze and alien creatures of the ocean floor, the hair-thin strands of glass at their center glowing with lasers encoding the world’s data. 

If, hypothetically, all these cables were to simultaneously break, modern civilization would cease to function. The financial system would immediately freeze. Currency trading would stop; stock exchanges would close. Banks and governments would be unable to move funds between countries because the Swift and US interbank systems both rely on submarine cables to settle over $10 trillion in transactions each day. In large swaths of the world, people would discover their credit cards no longer worked and ATMs would dispense no cash. As US Federal Reserve staff director Steve Malphrus said at a 2009 cable security conference, “When communications networks go down, the financial services sector does not grind to a halt. It snaps to a halt.”

A map of the world showing the dozens of fibre optic cable systems which stretch across the oceans, connecting continents and island chains. Some of these cables are extremely long. The map animates to show the cables laid down between 1989 and the present, with planned cables up to 2027 also displayed.

Corporations would lose the ability to coordinate overseas manufacturing and logistics. Seemingly local institutions would be paralyzed as outsourced accounting, personnel, and customer service departments went dark. Governments, which rely on the same cables as everyone else for the vast majority of their communications, would be largely cut off from their overseas outposts and each other. Satellites would not be able to pick up even half a percent of the traffic. Contemplating the prospect of a mass cable cut to the UK, then-MP Rishi Sunak concluded, “Short of nuclear or biological warfare, it is difficult to think of a threat that could be more justifiably described as existential.”

Fortunately, there is enough redundancy in the world’s cables to make it nearly impossible for a well-connected country to be cut off, but cable breaks do happen. On average, they happen every other day, about 200 times a year. The reason websites continue to load, bank transfers go through, and civilization persists is because of the thousand or so people living aboard 20-some ships stationed around the world, who race to fix each cable as soon as it breaks.

The industry responsible for this crucial work traces its origins back far beyond the internet, past even the telephone, to the early days of telegraphy. It’s invisible, underappreciated, analog. Few people set out to join the profession, mostly because few people know it exists. 

Hirai’s career path is characteristic in its circuitousness. Growing up in the 1960s in the industrial city of Yokosuka, just down the Miura Peninsula from the Ocean Link’s port in Yokohama, he worked at his parents’ fish market from the age of 12. A teenage love of American rock ‘n’ roll led to a desire to learn English, which led him to take a job at 18 as a switchboard operator at the telecom company KDDI as a means to practice. When he was 26, he transferred to a cable landing station in Okinawa because working on the beach would let him perfect his windsurfing. This was his introduction to cable maintenance and also where he met his wife. Six years later, his English proficiency got him called back to KDDI headquarters to help design Ocean Link for KCS, a KDDI subsidiary. Once it was built, he decided to go to sea with it, eventually becoming the ship’s chief engineer.

Captain Shoichi Suzuki sits in front of the control panels in the bridge of the Ocean Link.

Others come to the field from merchant navies, marine construction, cable engineering, geology, optics, or other tangentially related disciplines. When Fumihide Kobayashi, the submersible operator — a tall and solidly built man from the mountain region of Nagano — joined KCS at the age of 20, he thought he would be working on ship maintenance, not working aboard a maintenance ship. He had never been on a boat before, but Hirai enticed him to stay with stories of all the whales and other marine creatures he would see on the remote ocean.

Once people are in, they tend to stay. For some, it’s the adventure — repairing cables in the churning currents of the Congo Canyon, enduring hull-denting North Atlantic storms. Others find a sense of purpose in maintaining the infrastructure on which society depends, even if most people’s response when they hear about their job is, But isn’t the internet all satellites by now? The sheer scale of the work can be thrilling, too. People will sometimes note that these are the largest construction projects humanity has ever built or sum up a decades-long resume by saying they’ve laid enough cable to circle the planet six times.

KCS has around 80 employees, many of whom, like Hirai, have worked there for decades. Because the industry is small and careers long, it can seem like everyone knows one another. People often refer to it as a family. Shipboard life lends itself to a strong sense of camaraderie, with periods of collaboration under pressure followed by long stretches — en route to a worksite or waiting for storms to pass — without much to do but hang out. Kobayashi learned to fish off the side of the ship and attempted to improve the repetitive cuisine by serving his crewmates sashimi. (His favorite is squid, but his colleagues would prefer he use the squid to catch mackerel.) Hirai, an enthusiastic athlete, figured out how to string up a net on the Ocean Link’s helideck and play tennis. Other times, he would join the crew for karaoke in the lounge, a wood-paneled room behind an anomalous stained-glass door containing massage chairs, a DVD library, and a bar. A self-described “walking jukebox,” Hirai favored Simon & Garfunkel and Billy Joel, though he said the younger members of the fleet didn’t go in for it as much.

The world is in the midst of a cable boom, with multiple new transoceanic lines announced every year. But there is growing concern that the industry responsible for maintaining these cables is running perilously lean. There are 77 cable ships in the world, according to data supplied by SubTel Forum, but most are focused on the more profitable work of laying new systems. Only 22 are designated for repair, and it’s an aging and eclectic fleet. Often, maintenance is their second act. Some, like Alcatel’s Ile de Molene, are converted tugs. Others, like Global Marine’s Wave Sentinel, were once ferries. Global Marine recently told Data Centre Dynamics that it’s trying to extend the life of its ships to 40 years, citing a lack of money. One out of 4 repair ships have already passed that milestone. The design life for bulk carriers and oil tankers, by contrast, is 20 years. 

“We’re all happy to spend billions to build new cables, but we’re not really thinking about how we’re going to look after them,” said Mike Constable, the former CEO of Huawei Marine Networks, who gave a presentation on the state of the maintenance fleet at an industry event in Singapore last year. “If you talk to the ship operators, they say it’s not sustainable anymore.”

He pointed to a case last year when four of Vietnam’s five subsea cables went down, slowing the internet to a crawl. The cables hadn’t fallen victim to some catastrophic event. It was just the usual entropy of fishing, shipping, and technical failure. But with nearby ships already busy on other repairs, the cables didn’t get fixed for six months. (One promptly broke again.) 

But perhaps a greater threat to the industry’s long-term survival is that the people, like the ships, are getting old. In a profession learned almost entirely on the job, people take longer to train than ships to build.

KDDI Ocean Link

Key components of the KDDI Ocean Link

Drum engine
A powerful but delicate 12-foot diameter electro-hydraulic steel drum used for paying out and recovering cables and grapnels during repairs.

Linear cable engine
A conveyor comprised of 21 pairs of cable-gripping tires used for laying and retrieving cables.

Cable control room
A command center adjoining the bridge where cable tension is monitored and all cable operations are managed.

Cable tanks
Three tanks capable of holding a total of 2,800 miles of cable.

Bow Sheave
A rolling sheave that cables and grapnel ropes are passed over.

Bow and stern thrusters are used to maneuver into wind, waves, and currents to keep the ship stationary during repairs.

Remote submersible capable of operating at up to 8,000ft. Equipped with cameras, sensors, a robotic arm, and a powerful water jet for burying cables.

“One of the biggest problems we have in this industry is attracting new people to it,” said Constable. He recalled another panel he was on in Singapore meant to introduce university students to the industry. “The audience was probably about 10 university kids and 60 old gray people from the industry just filling out their day,” he said. When he speaks with students looking to get into tech, he tries to convince them that subsea cables are also part — a foundational part — of the tech industry. “They all want to be data scientists and that sort of stuff,” he said. “But for me, I find this industry fascinating. You’re dealing with the most hostile environment on the planet, eight kilometers deep in the oceans, working with some pretty high technology, traveling all over the world. You’re on the forefront of geopolitics, and it’s critical for the whole way the world operates now.”

The lifestyle can be an obstacle. A career in subsea means enduring long stretches far from home, unpredictable schedules, and ironically, very poor internet.

Kaida Takashi stands on the foredeck of the Ocean Link.

“Everyone complains about that,” said Kaida Takashi, a senior advisor at KCS, who is trying to get the Ocean Link set up with Starlink. It’s a generational difference, he said. For someone like him, a 62-year-old ham radio enthusiast, Wi-Fi barely fast enough to email is a luxury. Other industry veterans reminisced about the days when they felt fortunate to get faxes on board, or waiting for the mailbag in port, or the novelty of using the very cable they were laying to make calls from the middle of the ocean. But for people who grew up with an expectation of constant connectivity, the disconnection of shipboard life can cause visible discomfort. “It’s a part of them,” one industry veteran marveled of his younger colleagues. “They can’t let it go.” 

The industry’s biggest recruiting challenge, however, is the industry’s invisibility. It’s a truism that people don’t think about infrastructure until it breaks, but they tend not to think about the fixing of it, either. In his 2014 essay, “Rethinking Repair,” professor of information science Steven Jackson argued that contemporary thinking about technology romanticizes moments of invention over the ongoing work of maintenance, though it is equally important to the deployment of functional technology in the world. There are few better examples than the subsea cable industry, which, for over a century, has been so effective at quickly fixing faults that the public has rarely had a chance to notice. Or as one industry veteran put it, “We are one of the best-kept secrets in the world, because things just work.” 

TheThe Ocean Link spent two nights at sea before receiving orders to return. As they neared land, Hirai saw debris from the tsunami’s backwash floating in the water: fishing nets, tires, the roofs of buildings, the bloated body of what he guessed was a cow. 

The earthquake measured 9.1 on the Richter scale, the fourth largest ever recorded and the largest to ever hit Japan. But it was the series of tsunami waves that arrived half an hour later that dealt the most destruction, surging miles inland and sweeping buildings, cars, and thousands of people out to sea. The death toll would eventually climb to nearly 20,000, and the day would become a national tragedy referred to simply as “3/11.”

The full extent of the devastation was still becoming clear when the Ocean Link returned, but the disaster had already entered a new phase. One hundred and sixty miles north of Tokyo, a 50-foot tsunami wave overtopped a seawall protecting the Fukushima power plant, swamping the emergency generators that were cooling the reactors through its automatic post-quake shutdown and precipitating a nuclear meltdown. 

Hirai’s wife and son had made it back home to their house in Yokosuka, where they lived with Hirai’s parents. Kobayashi’s family, too, was safe. Some crew lost loved ones; others sent family to stay with relatives in the south out of fear of radiation. They all knew that they had only a few days before they would be sent back out to sea.

The disaster had severed phone lines and wrecked cell towers, causing phone service to cut out almost immediately after the earthquake struck. Instead, people turned to email, Skype, and other online services that were mostly able to route around damage to the network. There was a sense, according to one engineer’s postmortem presentation, that the internet was the only media that survived.

But its survival was more tenuous than the public knew. While the cables connecting Japan to the rest of the world survived the initial destruction, later that night, as millions of people tried to find their way home with trains stopped and power intermittent, engineers in Tokyo network operation centers watched as one cable after another failed. By the next morning, seven of Japan’s 12 transpacific cables were severed. Engineers working through the night and following days managed to shift traffic to those that remained, but the new routes were near their maximum capacity. The head of telecom company NTT’s operation center at the time estimated that if another cable failed, it would have lost all traffic to the US. With servers for most major internet companies located there, Japan would have effectively lost the internet. 

Normally, the sequence of repairs would be determined by whichever cable owner reported the fault first, but given the extraordinary circumstances, the usually self-interested cable owners agreed to defer to KCS. The priority was to repair a cable — any cable — as fast as possible. 

It was impossible to know the state of the cables on the ocean floor, so like forensic investigators, Hirai and the other engineers had to work with the sparse facts available. By having the cable landing stations on either side of the ocean beam light down their end of the line and time the reflections back, they were able to locate the faults nearest to them within a few meters. Most of the faults lay in deep water, in the canyons channeling into the Japan Trench. This, plus the timing of the faults, indicated it wasn’t the quake that broke them but the underwater avalanches it triggered.

“It hasn’t changed in 150 years… The Victorians did it that way and we’re doing it the same way.”

Submarine landslides are awesome events whose existence was only discovered in the 1950s, when scientists analyzed the timing of 12 cable faults that severed communication between Europe and North America two decades earlier. Before then, according to oceanographer Mike Clare, “It was assumed that deep water was boring and nothing happens down there.” In fact, the ocean floor is riven with mountains and canyons that experience avalanches that dwarf anything found on land, cascades of sediment and debris racing for hundreds of miles. Hirai had dealt with them in Taiwan in 2006, one of the most notorious events in the annals of cable repair. 

On December 26th, an earthquake dislodged sediment on Taiwan’s southern coast and sent it rushing 160 miles into the Luzon Strait, one of several global cable chokepoints. Nine cables were severed and Taiwan was knocked almost entirely offline. Banking, airlines, and communications were disrupted throughout the region. Trading of the Korean won was halted. The cables, buried under mountains of debris, were nearly impossible to find. It took 11 ships, including the Ocean Link, nearly two months to finish repairs.

Often in a multi-cable disaster like the Taiwan earthquake, every ship in the region comes to assist. But with Japan, there was an unprecedented complication: the majority of the faults were located offshore of the ongoing nuclear meltdown at Fukushima. Ship operators deemed assistance too risky, which meant that, for the time being, the Ocean Link was on its own. 

The crew felt not only duty bound to work but uniquely capable of doing so. They had dealt with radiation before, though not at this scale. In 1993, shortly before the Ocean Link was to lay a cable linking Japan, Korea, and Russia, they learned the Soviets had dumped radioactive waste in the ocean along the planned route. With some trepidation, KCS proceeded with the job. They bought Geiger counters and protective gear, flew in nurses from the US with chemical weapons training, and scanned the water for radiation as they went. When none was detected, they put the gear in storage. 

Now, as they readied the ship for departure, an employee was dispatched to the depot to find the old radiation gear. A local university donated a few more sensors and trained the crew on how to use them. 

They decided to begin with the same cable they had just finished repairing when the earthquake struck. On a drizzling afternoon eight days after returning to port, with smoke still rising from the Fukushima power plant, the Ocean Link set back out to sea.

Cables are wrapped around a large metal structure in the KCS depot.

ToTo the extent he is remembered, Cyrus Field is known to history as the person responsible for running a telegraph cable across the Atlantic Ocean, but he also conducted what at the time was considered an equally great technical feat: the first deep-sea cable repair. 

Field, a 35-year-old self-made paper tycoon, had no experience in telegraphy — which helps explain why, in 1854, he embarked on such a quixotic mission. Though small bodies of water like the English Channel had been bridged by telegraph, failure was routine and costly. Cables shorted out, snapped under tension, snagged on rocks, were sliced by anchors, twisted by currents, tangled around whales, attacked by swordfish, and devoured by a “miserable little mollusc” called the Teredo worm with an appetite for jute insulation. 

Field fared no better. Twelve years after he began, he had endured severed cables, near sinkings, and had one “success”: a cable laid in 1858 that prompted celebrations so enthusiastic that revelers set fire to New York City Hall. The cable failed weeks later.

Field tried again seven years later only for the cable to snap halfway across the Atlantic. The next year, he set out yet again, promising not only to finally lay a working transatlantic cable but to recover the broken cable and finish that one, too. 

By that time, a crude method had been developed for fixing cables in shallow water. A ship would drag a hooked grapnel anchor across the seafloor, until, like the tremor of a fishing line, increasing tension showed they’d caught the cable, which they would then haul on board to fix. Field’s plan was basically this but bigger: bigger hooks, stronger rope, more powerful winding engine, all aboard the largest ship afloat, a passenger liner called the SS Great Eastern that had been retrofitted for the mission. William Thomson, the project’s scientific adviser and the future Lord Kelvin, did the math and deemed it feasible. 

“When it was first proposed to drag the bottom of the Atlantic for a cable lost in waters two and a half miles deep, the project was so daring that it seemed to be almost a war of the Titans upon the gods,” wrote Cyrus’ brother Henry. “Yet never was anything undertaken less in the spirit of reckless desperation. The cable was recovered as a city is taken by siege — by slow approaches, and the sure and inevitable result of mathematical calculation.”

Humans continue to be by far the single greatest threat to cables

Field’s crew caught the cable on the first try and nearly had it aboard when the rope snapped and slipped back into the sea. After 28 more failed attempts, they caught it again. When they brought it aboard and found it still worked, the crew fired rockets in celebration. Field withdrew to his cabin, locked the door, and wept.

Cable repair today works more or less the same as in Field’s day. There have been some refinements: ships now hold steady using automated dynamic positioning systems rather than churning paddle wheels in opposite directions, and Field’s pronged anchor has spawned a medieval-looking arsenal of grapnels — long chains called “rennies,” diamond-shaped “flat fish,” spring-loaded six-blade “son of sammys,” three-ton detrenchers with seven-foot blades for digging through marine muck — but at its core, cable repair is still a matter of a ship dragging a big hook along the ocean floor. Newfangled technologies like remotely operated submersibles can be useful in shallow water, but beyond 8,000 feet or so, conditions are so punishing that simple is best.

A schematic view of the ocean depths, with the Ocean Link at the surface. A cable leads down from the ship into the depths. We pass through the Euphotic (Sunlight) zone where familiar animals live, before hitting the twilight zone 656 ft below sea level. The fauna gets more exotic and the light dimmer until we reach the Bathypelagic (Midnight) zone, at 3,280 ft. Here we see giant squid and anglerfish. Travelling further, the Abyssopelagic (abyssal) zone starts at 13,123 ft, and features a couple of weird fish and cephalopods. Finally, the cable terminates in a grapnel in the Hadopelagic (hadal) zone at 19,685 ft. It has hooked its target.

The deepest repair the Ocean Link conducted in the aftermath of the 2011 earthquake was 6,200 meters (20,340 feet).

“It hasn’t changed in 150 years,” said Alasdair Wilkie, chair of the Atlantic Cable Maintenance & Repair Agreement (ACMA). “The Victorians did it that way and we’re doing it the same way. I just think it’s one of those things that, if it ain’t broke, don’t fix it.”

Nor have the causes of faults changed in the last century and a half. The first submarine cable, strung across the English Channel in 1850, survived for a single day before — in what may be apocryphal cable industry slander — a French eel fisherman accidentally hooked it, sliced off a piece, and came ashore bragging about his discovery of a new type of metal seaweed. In his history of global telecommunications, How the World Was One, Arthur C. Clarke declared this the first blow in a war between cable companies and other users of the sea that has continued to this day.

Humans continue to be by far the single greatest threat to cables. Fishing accounts for about 40 percent of faults, according to the International Cable Protection Committee (ICPC). Bottom trawling, particularly as it extends into new regions and deeper water in pursuit of depleting fish stocks, is especially damaging. Last year, Chinese fishing vessels severed cables to one of Taiwan’s outlying islands, triggering an international incident. (Severing Taiwan’s cables is one of the first moves in war games of a Chinese siege.) The year before, trawlers cut multiple cables off the coast of Scotland, knocking several islands offline. Dragged anchors from cruise ships, cargo vessels, and pleasure boats are another common culprit. Last year, an improperly moored mega yacht knocked out all communication for the Caribbean island of Anguilla.

One thing that is not a threat to cables, many in the industry are eager to emphasize, is sharks. The idea that sharks eat submarine cables — repeated in news stories and even some government reports — stems from an incident in the late 1980s when AT&T was testing one of the first subsea fiber optic cables off the coast of the Canary Islands. The cable kept suffering mysterious faults, and when a repair ship hauled it up, teeth were found embedded near the breaks. A study was launched. Bell Labs scientists measured jaw radii and bite strength and, at one point, tried to feed captured sharks samples of cable. The culprit turned out to be a deepwater crocodile shark, possibly attracted to the electromagnetic field emitted from the power repeaters. 

Wrapping cables in metal tape seems to have solved any shark problems. Nevertheless, when an old YouTube video of a shark biting a cable went viral in 2014, it incited global news coverage. The ICPC issued a statement (“Sharks are not the nemesis of the internet — ICPC findings”) saying that it didn’t even look like a data cable, fish bites haven’t caused a fault in many years, and that humans are almost always to blame. Yet the myth endures, possibly because there is something satisfying about the idea of the modern world being brought down by the appetites of a prehistoric creature, and possibly because the idea of sharks eating the internet seems only slightly less improbable than the internet consisting of tubes on the bottom of the sea.

OnOn March 22nd, with the world’s attention fixed on the crisis at Fukushima, the Ocean Link reached its worksite 160 miles to the south. They had chosen one of the faults farthest from the meltdown, but the winter wind was blowing from the north and the crew remained inside the ship until it was deemed safe to go outside. 

As the chief engineer and one of the oldest members of the crew, Hirai felt it was his duty to perform the radiation checks. He pulled on the slick yellow coveralls and boots, strapped on a mask and goggles, and opened the heavy steel door leading to the foredeck. 

The sky was overcast and low, and the ship rocked on a building swell as Hirai walked out onto the pocked green-painted deck and held out the wand of his Geiger counter to see what the wind carried. To his relief, it registered only background radiation. Next, he walked to the side and lowered a sensor into the sea. Again, nothing. He would do it all again in two hours, but for now, work could begin. 

They spent the first day and night surveying the worksite, moving slowly along the cable route while measuring the depth and current. Conditions worsened overnight and dawn greeted them with 15-foot waves and gale-force winds, too violent for delicate cable work. They would have to wait.

At the most basic level, a broken cable is fixed by patching the break with a piece of new cable, but because the break is miles away on the ocean floor, this must be done in several steps. The first step is to cut the cable near the break (often, the cable will have been damaged but not cleanly severed, and cables are laid with so little slack that they cannot be pulled to the surface in one piece). This is done by dragging a bladed grapnel across the cable in a so-called “cutting drive.” The ship then swaps the bladed grapnel for a hooked one and catches one end of the severed cable, hoists it to the surface, and attaches it to a buoy. Then they catch the other cable end, splice the spare cable to it, and tow the spare cable back to the first buoyed cable to complete the patch. The ship is now holding a working cable but one that is considerably longer than it used to be. This process of bringing each cable end to the surface separately means that every repair makes a cable longer — in deep water, by several miles. In order to minimize slack that could get tangled and snagged, the loop of new cable is towed to the side of the original route until it can lay taut on the ocean floor once again.

The Ocean Link had repaired this same stretch of cable five years earlier, which meant they had already added the slack required to bring it to the surface, no cutting required. It should have been sitting on the seafloor in the form of a 12-mile loop. If they could catch it, Hirai reasoned, they would save time and — this was important — precious spare cable. Every cable ship is stationed next to a depot with a certain amount of spare cable for each system in its jurisdiction. If the Ocean Link used too much on their first repair, it would take six months to manufacture and deliver enough new cable to fix the remaining faults.

By the afternoon, the Ocean Link was still plunging through heavy seas, but with the storm predicted to pass overnight, they decided to begin. From the arsenal of yellow-enameled grapnels strapped to the foredeck, Hirai selected a “jamming-type sliding prong,” a mace-like implement comprised of two metal bars studded with foot-long barbs, well suited for dragging across rocky seabed without getting stuck. They lowered it over the bow sheave and into the water. The ocean floor was more than three miles down, and it took the grapnel more than six hours to hit bottom. The Ocean Link began to move slowly forward.

From this point onward, Hirai or another engineer would be in the cable control room — an instrument-filled command center behind the bridge — their attention fixed on the tension meter, a circular dial set into a pale green wall. The retro-looking analog gauge was less precise than a digital one but far better for intuitively conveying changes in tension than a jittery numerical readout. The steady wavering of its arm would mean the grapnel was plowing through the gray ooze of the ocean floors. A staccato spike; they had hooked a rock. A steady rise; the cable had been caught. Part of being an effective chief engineer, Hirai found, was the ability to read what was happening on the ocean floor from the limited information of the moving dial. 

At 6AM the next day, the engineer on duty saw the telltale rise of a caught cable, and the Ocean Link came to a stop. They had hooked the cable on the first run — rare in an earthquake repair — and began to reel it in.

The ships are aging; the people are aging; and it’s unclear where the money will come from to turn things around

Almost immediately, there was a sign something was amiss. The tension was rising too high too fast. The cable must be pinned under debris, Hirai thought. He ordered the winding engine to slow lest the cable snap, reeling in the grapnel at a grinding 10 feet per minute. 

The morning passed, then the afternoon, Hirai suiting up every few hours to check for radiation. The drum engine continued its slow rotation. Night fell. Half past midnight, after 19 hours of winding, the cable reached the surface. 

The grapnel came over the bow and was illuminated by the deck lights. Hirai was horrified at what he saw. They had caught the cable, but it was mangled unlike anything he had seen before. Hooked around one of the grapnel’s lower barbs, the cable’s polyethylene and wire sheath had been stripped by extreme tension and sprang in coiled loops like Slinkys put through a dryer. 

It was a dangerous situation. There was no telling how much tension a cable this badly damaged could withstand. It was like a three-mile rubber band stretched tight from the ocean floor, being tested with every rocking wave. If it snapped, the grapnel would fly across the deck, killing anyone it hit before smashing into the cable engine room. 

They had to get the cable off the ship, but doing so involved working closely with the explosive bundle hovering, taut, above the deck. First, crew members lashed chains to either end of the cable to take the tension off the grapnel, which they then swapped for a version with a sharp blade at its center, typically used for severing cables on the ocean floor. This done, they evacuated the foredeck. 

The grapnel, cable, and chains were slowly lowered back over the prow and into the sea, the ship maneuvering delicately to minimize any sudden changes in tension. Once the cable was safely beneath the waves, they released the chains. Suddenly, pulled tight over the blade, the cable split and sank back to the ocean floor. 

For Hirai, relief at a disaster averted was soon followed by foreboding. The landslides created by the earthquake must have been far greater than he had imagined, dragging the cable for miles, mangling it, and burying it beneath who knew how much debris. He couldn’t think how to proceed.

The cable tension meter and other indicators in the Ocean Link’s cable control room.

DebatesDebates about the future of cable repair have become a staple of industry events. They typically begin with a few key facts: the ships are aging; the people are aging; and it’s unclear where the money will come from to turn things around. 

For much of the 20th century, cable maintenance wasn’t a distinct business; it was just something giant, vertically integrated telecom monopolies had to do in order to function. As they started laying coaxial cables in the 1950s, they decided to pool resources. Rather than each company having its own repair vessel mostly sitting idle, they divided the oceans into zones, each with a few designated repair ships. 

When the telcos were split up at the turn of the century, their marine divisions were sold off. Cable & Wireless Marine became Global Marine. AT&T’s division is now the New Jersey-based SubCom. (Both are now owned by private equity companies; KCS remains a subsidiary of KDDI.) The zone system continued, now governed by contracts between cable owners and ship operators. Cable owners can sign up with a nonprofit cooperative, like the Atlantic Cable Maintenance & Repair Agreement, and pay an annual fee plus a day rate for repairs. In exchange, the zone’s three ships — a Global Marine vessel in Portland, UK, another in Curaçao, and an Orange Marine vessel in Brest, France — will stand ready to sail out within 24 hours of being notified of a fault.

This system has been able to cope with the day-to-day cadence of cable breaks, but margins are thin and contracts are short-term, making it difficult to convince investors to spend $100 million on a new vessel.

“The main issue for me in the industry has to do with hyperscalers coming in and saying we need to reduce costs every year,” said Wilkie, the chair of the ACMA, using the industry term for tech giants like Google and Meta. “We’d all like to have maintenance cheaper, but the cost of running a ship doesn’t actually change much from year to year. It goes up, actually. So there has been a severe lack of investment in new ships.”

At the same time, there are more cables to repair than ever, also partly a result of the tech giants entering the industry. Starting around 2016, tech companies that previously purchased bandwidth from telcos began pouring billions of dollars into cable systems of their own, seeking to ensure their cloud services were always available and content libraries synced. The result has been not just a boom in new cables but a change in the topology of the internet. “In the old days we connected population centers,” said Constable, the former Huawei Marine executive. “Now we connect data centers. Eighty percent of traffic crossing the Atlantic is probably machines talking to machines.”

A black and white photograph of the bow of a cable ship.

Maintenance providers regard these changes with ambivalence. The cable boom means there will be no shortage of cables to fix, but it also means a future of negotiating with a handful of tech giants that can use their tremendous buying power to squeeze ship operators further. 

Market forces pose one challenge; geopolitics another. Tensions with China, including the increasing difficulty of getting permission to repair cables in the contested waters of the South China Sea, are contributing to decisions to route new systems through the Philippines and other less direct passages. Conflict in the Middle East has the industry looking nervously at the Red Sea, an infamous cable chokepoint: in February, a freighter struck by Houthi rockets dragged its anchor across three crucial connections between Asia and Europe, degrading connectivity and raising the frightening prospect of conducting repairs under fire. The Red Sea vulnerability has in turn renewed interest in an Arctic route, made potentially feasible by melting sea ice, though, for years, one of the fatal flaws of this proposal has been the question of who would repair such a cable, there being no ice-capable maintenance vessels.

These and other recent events, like the 2022 Nord Stream pipeline explosion, have led governments to take a greater interest in cable security, often focusing on the specter of a deliberate attack. Late last year, NATO convened a symposium on undersea infrastructure and the future of “seabed warfare,” while the UK commissioned naval vessels to patrol their subsea connections. Meanwhile, the European Union, India, and other governments have proposed investing in maintenance vessels directly.

“The amount of ships is relatively limited, and there are a number of places where it could get critical,” said Christian Bueger, the lead author of a 2022 EU Parliament study on threats to subsea data infrastructure. As part of the study, he visited a cable repair ship in Cape Town, South Africa. It was old, he said, with oily, clanging machinery demanding hard physical labor — the opposite of the clean digital space he associated with the internet. One of his recommendations was that governments figure out a way to invest in cable fleets rather than rely on companies focused on cost cutting and efficiency.

The situation of SubCom illustrates the industry’s strange moment. The company has been withdrawing from maintenance work, according to industry sources, in order to focus on more lucrative installations, many of which are for Google. At the same time, the company is increasingly intertwined with the US government, which waged a pressure campaign to help SubCom beat China’s HMN Tech for the contract to build a major Asia-to-Europe cable, according to Reuters. SubCom also recently won a contract to operate the US’s first “cable security fleet.”

Like the involvement of the tech giants, industry veterans regard this new government interest with ambivalence. More funding would be welcome, but the world of subsea cables is one of unforgiving tradeoffs, and it’s easy for well-intentioned policies to go awry. One often proposed solution, for example, is to corral cables into protected corridors, which can make them easier to guard against malicious actors but also makes it possible for a single landslide to take them all out at once.

“Did any of us know that we went viral on TikTok?”

Secrecy, too, is a double-edged sword. Classifying cable locations might make them more difficult to attack while worsening exposure to what is their actual greatest threat: fishing accidents and other forms of human negligence. Greater secrecy could also heighten the tension between the industry’s near-total obscurity and its need for new recruits. Ships are a relatively easy problem to solve; they just take money. People take years to train.

The submarine cable world has never been particularly public. The industry is small and competitive, and cable owners don’t want their cables to get a reputation for breaking, so they bind maintenance providers with nondisclosure agreements. The result is that in the rare case that a fault reaches public awareness, ship operators almost never talk about it. Add in national security concerns, and the result is a code of silence that pervades the entire business. (Which is also why many of the sources in this story are “industry veterans” or other anonymous descriptors.) The industry has begun to recognize that this poses a recruiting challenge.

In 2022, the industry organization SubOptic gathered six cable employees in their 20s and 30s for a panel on the future of the industry. Most of them had stumbled into their jobs inadvertently after college, and the consensus was that the industry needed to be much better about raising public awareness, especially among the young. 

“I don’t know if anyone saw, but during the pandemic, submarine cables actually went viral on TikTok,” said one panelist, a young cable engineer from Vodafone. “People didn’t know they existed, and then suddenly, out of nowhere, they were viral. I think it’s engaging with youth and children through their own avenues — yes, you can have science museums and things like that, but they are online, they are on their iPads, they’re on their phones.”

“We’ve got some pretty senior decision-makers and influencers in the subsea cable industry here,” said one audience member. “Did any of us know that we went viral on TikTok?” he asked, to laughter. 

“As this panel rightfully said upfront, it’s not that we have a brand problem,” said another audience member, “we just don’t have a brand at all.”

ItIt took the Ocean Link a month to complete its first repair. Failed grapnel runs, fishing gear entanglements, repeated radiation checks, and storms: it had been among the most difficult repairs Hirai had faced. They continued to work through the spring, but by June, they faced a dilemma. 

Many of the remaining faults lay 50 miles off the coast of Chiba, deep in the Japan Trench, where eight different cable lines passed near and sometimes over each other. It was a cable chokepoint, and a landslide must have crashed down and wrecked them all. It would be difficult to catch one without cutting its neighbor. Even if they could, it wasn’t clear they had enough spare cable to fix each fault individually, with all the loops of slack they would need to add to bring the cables to the surface. 

Hirai decided the only solution was to abandon the tangled mess and lay a new system on top of it. It would mean abandoning miles of cable as well as a branching unit: a 2,000-pound device that splits one cable into two different lines going to two destinations. But by reducing the number of loops, it would reduce the amount of cable required. Even then, it wasn’t clear they had enough. They did, however, have a lot of small bits of cable they had been careful to salvage during previous repairs — three miles here, five miles there. With a lot of work, they could be spliced together.

Takashi Kurokawa had joined KCS 12 years earlier, after hearing about the company from a teacher while in engineering school. Unlike many of his colleagues who moved roles every few years, after Kurokawa learned to joint, he just kept jointing. He enjoyed the way jointing’s strict rules and standards for success created a structure within which he could push himself to attain ever greater precision and speed.

Takashi Kurokawa preparing to splice a fiber.

The work is extraordinarily delicate. Cables must be stripped of their polyurethane sheaths, copper conducting tubes, wire armor, and enamel coating until the clear glass threads themselves are exposed. Kurokawa then takes a glass strand from each cable, cleans them in a sonic bath (touching them risks damage and splinters), cleaves their ends at perfect right angles, and places them inside a black toaster-sized box called a fusion splicer, their ends almost but not quite touching. In an instant, the device aligns the ends and zaps an electric arc between them, melting the glass together. Kurokawa then winds the newly spliced fiber into a metal tube called a joint box and does it all again for the next fiber strand. The entire process can take 20 hours, with Kurokawa and his team working in shifts. Every step demands hunched, jeweler-like focus as they seek perfect precision — not in a seismically isolated clean room but in the belly of a rocking ship. Each joint is expected to function untouched under crushing pressure for at least 25 years.

To speed matters, they decided to assemble what they could in port at Yokohama, with the Ocean Link moored and relatively stable. Working in shifts over 10 days, Kurokawa and his colleagues spliced 10 joints, four repeaters, and a branching unit — assembling a three-part, 100-mile system from the spare bits of cable they had on hand. At night, he dreamed of winding cables back and forth between storage tanks to get at the segments he needed. On June 26th, they tested the apparatus. It worked. They set sail the same day, with no estimate for how long it would take.

Hirai had mapped out the plan to a meticulous 23 steps. They began by severing the cable running from the branching unit to Murayama in the south, catching the landward end, splicing the new cable to it, and sailing northward to the point where they planned to deposit the new branching unit. There, they attached the cable to a buoy and lowered it into the ocean. Then they were off to the northern cable, which they caught, spliced, and pulled back to the buoy. It took 12 days to get here, and now came the difficult part.

The final splice is the most precarious moment of the repair. On the first splice, the ship can pivot 360 degrees around the dangling cable in order to angle into the wind and waves and maintain position. But on the second splice, there are two cables hanging off the prow, and the ship’s maneuverability is far more restricted should the weather turn foul.

With the branching unit, they had to complete two final splices — one for each leg — then deposit the whole apparatus to the ocean floor intact. This, the Ocean Link crew knew, would be its own challenge. A 2,000-pound weight dangling for miles through the water column can do funny things. In 2008, the Ocean Link was called to recover a branching unit that another cable ship accidentally dropped into the Japan Trench while trying to deploy it. With a typhoon approaching, they caught the cable, brought up the unit, and fashioned a webbing loincloth-like harness between the unit’s two legs for additional support before lowering it back to the bottom.

They would again be working in deep water — nearly four miles — but what troubled Hirai was the current. A powerful river of warm water called the Kuroshio Current snakes unpredictably up from the south along Japan’s coast, and it happened to be racing through the worksite at four knots, aquamarine and glittering in the summer sun. The Ocean Link would have to constantly adjust its thrusters to maintain position against the stream and prevent the branching unit from banging against the hull as it descended. But the weather was fair and the swell was light, so they decided to proceed. 

Hirai, Kurokawa, Kobayashi, and more than a dozen other members of the crew assembled on the foredeck. The white-painted prow glared bright in the sun as the branching unit was brought out, a metal tube with two black accordion legs that tapered to slender cables. They had drilled this maneuver before leaving port. Clad in hard hats, the crew gingerly placed it on a metal dolly and strapped it down. Hirai tied yellow webbing between its legs to form a harness and affixed a safety rope. Kurokawa stood by the prow, watching the unit as it was rolled toward him. Kobayashi stood back by the drum engine, watching the cable unspool and worrying what would happen if it snapped, envisioning weeks of splicing plunging to the ocean floor.

A group photo of the crew of the Ocean Link in 2011. The ship itself is in the background.

The ship’s thrusters hummed and moved the Ocean Link ever so slowly backward. One end of the branching unit lifted off the dolly as it was pulled up onto the bow sheave. To an observer, the ship would look nearly stationary as the current flowed around it. The unit went over the top of the prow and descended, hanging from its harness, until it slipped below the surface and out of sight.

It was August by the time the Ocean Link finished the branching unit repair. Other ships, deeming the crisis at Fukushima stable enough to work, had arrived to help. Hirai sometimes advised them on the area’s tricky currents and rugged bathymetry, but mostly, they stayed out of each other’s way; the last thing you want to do is tangle two grapnels.

The final repair was an easy one. They had to finish the job that had been interrupted by the earthquake nearly five months earlier. They returned to the site where they had made their rushed escape, deployed the submersible, and buried the rest of the cable beneath the sand. 

The repair was so close to port that there was no time to celebrate during their return, nor was there much of a mood to do so. The earthquake had caused more than 20 faults, and the Ocean Link had repaired 11 of them. It had taken 154 days of continuous work. They had missed a time of national mourning, school graduations, harvest celebrations, and the slow resumption of normalcy. 

After they docked, the crew departed for their homes. Hirai stayed behind to finish writing his final daily report, then made for home as well. As he rode the train back to Yokosuka, he watched his fellow passengers absorbed in their phones. We completed the job, he thought with satisfaction, and they have no idea.

Creative Director: Kristen RadtkePhoto Editor: Amelia Holowaty KralesEngineer: Graham MacAree

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