HAMBURG — Ever since humanity conquered the oceans, we’ve been shipping valuable goods across the water. The winds that once billowed sails have long been replaced by roaring engines, and cargoes of damask, silk and rum have given way to towering stacks of 20-foot containers.
Yet, despite all the technological leaps, the oceans remain the arteries of global trade. But today, the most valuable commodity of the 21st century travels across these waters much faster than the swiftest ship, or even jet plane. That commodity is data.
Protected beneath millions of cubic kilometers of water, hundreds of submarine data cables crisscross the seabed, connecting continents like invisible lifelines. Some of these cables are so astonishingly long that you could loop them around the Earth. And yet, they’re barely thicker than a garden hose.
Without these communication links, the modern lives of billions would grind to a halt: they carry the lion’s share of global data traffic.
But the vast, watery expanse that conceals and shields these cables is growing more restless — and so is the geopolitical landscape. The danger of these vital “nerves” of the Internet being seriously compromised is no longer just a distant threat.
The cloud is not in the sky
It is probably not clear to everyone how important the submarine cables are for the daily lives of billions of people: whether you send an email to your boss or start the next episode of Friends — each time, information rushes through the cables in the form of light pulses, often heading west, towards the data centers of the U.S.
Be honest: were you aware of this? When you asked yourself how the Internet actually gets to you, did you imagine satellites orbiting the globe in the silence of space? Scientist Michael Clare, who researches the risks to the submarine cable network, sets the record straight: “The cloud is not in the sky, it is under the sea.”
Satellites only transport a very small proportion of the signals that make up global data traffic: something in the single-digit percentage range. They are slower to transmit than fiber optic cables — and keeping this so-called latency as low as possible is crucial in the financial market, for example.
Satellites are also expensive and less durable. Their bandwidth, the amount of data transmitted within a certain period of time, simply cannot match that of a submarine cable.
Cables are unsexy.
But then why are satellites stealing the show while cables do all the work? Nicole Starosielski, a professor at the University of California, Berkeley, who’s spent years researching global communications infrastructure and submarine cables, has an answer: “Cables are unsexy. You throw some hoses off a ship — big deal. It’s just not as thrilling as rockets shooting things into space.”
The process of laying submarine cables is indeed far from glamorous. Specially equipped ships loaded with massive cable drums unfurl the cables along pre-planned routes. Beforehand, extensive surveys ensure the seabed is clear of obstacles and marine ecosystems remain undisturbed.
The cables themselves are fortified with layers of metal and plastic, and near coastlines, where the waters are busier, they’re buried beneath the seabed using cable plows. Out in the open sea, they lie snug on the ocean floor like giant, slumbering sea serpents — and can keep working for decades. That is, unless something unexpected happens.
Data is the new oil
Each cable is anchored at landing stations on both ends. Germany, for instance, has six such stations along its North and Baltic Sea coasts. These, in turn, connect to a sprawling web of land cables across the country.
Since September 2023, the German submarine cable landing stations have been defined as part of the critical infrastructure; they are now considered “of particular importance for the functioning of the community” and must be protected. But cybersecurity expert Manuel Atug thinks this recognition came too late. In today’s world, the value of a stable communication network cannot be overstated. And neither can the value of the data these cables carry, as Atug notes the now familiar formula: “Data is the new oil.”
So, are these data pipelines secure enough?
The fact that most people have never heard of submarine cables suggests the industry has done a decent job keeping them under the radar, says Starosielski. But that doesn’t mean the cables are invincible: they face multiple threats. And we are not just talking about the sharks biting them for the sake of it: it’s enemy sabotage and climate change.
Hurricanes and sabotage
The ocean has always been a force to reckon with — storms, tsunamis, and surging waves are nothing new. But Michael Clare, from the National Oceanography Centre in Southampton, UK, has found that climate change is multiplying the risks. As global warming shifts ocean currents, winds, and wave patterns, tropical cyclones could increasingly intersect with cable routes.
According to researchers, coastal areas are particularly at risk: rising sea levels can lead to flooding and storm surges, which is a problem especially for cable landing stations in low-lying coastal areas. The fact that coasts are eroding does not help either.
The greatest threat to submarine cables isn’t nature—it’s humans.
Earthquakes could also become more frequent due to climate change (Seismologic Research Letters: Bohnhoff et al., 2024 ). Fiber optic cables are not always equipped to withstand earthquakes, as was observed off the coast of West Africa in March: In some countries — Liberia, Ghana, Burkina Faso and Togo — the Internet almost completely failed after several cables were damaged at a depth of around three kilometers. “Seismic activity” on the seabed is suspected to be the cause.
Chinese and Russian ships
But the greatest threat to submarine cables isn’t nature — it’s humans. Specifically, fishing vessels. Starosielski explains that the majority of cable damage occurs when fishing nets or ship anchors inadvertently cut through them. But this risk, too, explains Starosielski, is deeply connected to climate change.
“It is changing the patterns for fishing,” she says. The oceans are getting warmer, and with the temperature, currents are changing — and with them the movements of schools of fish. Dwindling stocks encourage fishing fleets to increasingly head for new, deeper areas of the ocean. And in trying to catch them, fishing boats often accidentally cut cables that they simply don’t know about.
The third danger, besides accidents and misfortunes, is rare but worrying. “Intentional sabotage is at the bottom of the list,” says scientist Starosielski. But it could be increasing. As early as 2017, the NATO commander of the submarine forces said in The Washington Post : “Russian underwater activity near submarine cables is now at a level we have never seen before.” Putin clearly has an interest in underwater infrastructure.
It is not always possible to determine whether it’s accidents or sabotage.
In October 2023, Swedish and Finnish authorities reported that submarine cables connecting the countries with Estonia had been damaged. A Chinese ship was suspected of having dragged its anchor more than 100 nautical miles above the bottom. A Russian ship was also said to have been in the waters at the time the incident occurred.
It is not always possible to clearly determine whether such incidents are sabotage. And the line between accident and attack is not always clear: when three data cables were severed in the southern Red Sea in spring 2024 , data traffic between Europe and Asia was disrupted. It is now assumed that the anchor of a cargo ship from the Houthi militia in Yemen was responsible: it might have been a mistake, but the Houthis had previously threatened to attack the cables.
Safety precautions
A severed cable does not necessarily lead to a total failure of the Internet. At least not in places where more than one cable is connected. The more alternative routes there are, the easier it is to reroute data traffic. If a cable needs to be repaired, the operators send one of the cable-laying ships, which are also equipped for repairs. In the meantime, data traffic runs through one of the other lines.
Still, this workaround isn’t seamless. Manuel Atug likens it to a highway closure: “If the highway is blocked, everyone takes the backroads, and traffic jams are inevitable. Data packets get stuck in traffic the same way because cables have finite capacity.”
Redundancy also plays a role in how likely enemy attacks on the cables are. “The question is: who is the enemy and what is the desired effect of an attack?” says the scientist. “If the enemy is Tonga and you want to cut Tonga off from the Internet, that is absolutely feasible. A volcano has already done that. But that is only an effective strategy if you want to specifically attack a region that is only connected to the global network by a few cables.”
Google, Meta and Microsoft have been investing in cable security for years.
In parts of the world like Europe or North America, physical attacks on a few cables can cause major diplomatic crises, but the effects on Internet usage are more like a small digital hiccup.
Melting ice, new hopes
The cables are not perfectly protected. But their protection may be just enough, considering the effort required to attack a cable that is not precisely mapped and is as thick as a garden hose and located kilometers deep, and that the potential return is limited.
And yet, better safe than sorry: there is a need to expand the global submarine cable network securely and reliably, because data traffic will continue to grow. Tech companies such as Google, Meta and Microsoft have been investing in cable security for years.
Interestingly, climate change, which poses so many threats, could also create opportunities. The melting Arctic ice might enable new cable routes across the North Pole. Where the once eternal ice is gradually thinning in summer, ships could soon lay submarine cables. If the Arctic Ocean freezes over in winter, then the cables would be additionally protected from attacks by the ice layer. They would be inaccessible to enemy attackers, although repair efforts would also become more challenging.
This possibility is already more than just a vague idea. The Far North Fiber project wants to go through the Arctic: with a 14,500-kilometer-long cable that would connect Europe with Japan, with landing stations in Alaska, Canada, Norway, Finland and Ireland. The EU is providing some of the funding for this.
It would be the digital manifestation of the Northwest Passage — only now, the goods being transported aren’t silk or spices but terabytes of data, the most valuable commodity of the 21st century.
