The earth trembled on November 18, 1929, near Newfoundland’s Burin Peninsula. 28 people were killed when a 7.2-magnitude earthquake shook the night, toppling chimney pots onshore and sending a 13-meter tsunami crashing into coastal communities. Even on its own, it was devastating. However, hours later, something else occurred beneath the Atlantic’s surface that no one could see or even knew to search for. The earthquake caused a submarine landslide that traveled more than a thousand kilometers from the epicenter while moving silently through the deep water at 50 to 70 knots. Transatlantic subsea cables, the most cutting-edge communications technology of the time, were in its path. Twelve of them lost it. There were a total of twenty-eight breaks. For a moment, the world became somewhat quieter.
The striking thing about that incident, almost a century later, is how much more disastrous its contemporary counterpart would be. Because telegraph messages are no longer carried by those thin wires on the ocean floor. They have everything with them.
| Category | Details |
|---|---|
| Infrastructure Type | Submarine Fiber-Optic Communication Cables |
| First Deployed | 19th century (transatlantic telegraph cables) |
| Total Length Worldwide | Over 1.3 million km — more than 32× Earth’s circumference |
| Active Cables Worldwide | Over 400 |
| Share of Global Internet Traffic | ~99% of all inter-continental digital data |
| Typical Cable Diameter | Telecom: ~2–5 cm (roughly the width of a hosepipe); Power cables: 7–21 cm |
| Installation Cost (Telecom) | ~€25,000–€45,000 per km; Power cables: €1–2 million per km |
| Annual Damage Incidents | 150–200 incidents per year globally |
| Leading Cause of Damage | Accidental human activity — fishing trawlers and ship anchors (70–80% of faults) |
| Notable Historical Incident | 1929 Newfoundland earthquake — triggered submarine landslide that snapped 12 cables in 28 places |
| Emerging Threat | State-sponsored sabotage (Baltic Sea incidents, 2024–2025); suspected use of anchors by foreign vessels |
| Key Private Investors | Google, Meta (heaviest investors); also Microsoft, Amazon |
| Recent Military Response | NATO Baltic Sea flotilla deployed early 2025 to monitor and protect cable corridors |
| Deep-Sea Placement | Below 2,000 m: laid directly on seafloor; shallower waters: buried for protection |
There are currently more than 400 operational submarine cables that span more than 1.3 million kilometers across all of Earth’s oceans, a total length greater than 32 times the planet’s circumference. The cables would span the Sun’s diameter if they were laid end to end. Approximately 99% of all intercontinental internet traffic is carried by them, including phone calls, emails, cloud data, streaming video, financial transactions, medical records, and military communications. It all travels through cables that are often no wider than a garden hose. The foundation of contemporary digital life is something you could hold in one hand, buried beneath miles of dark water, mostly hidden from view and, for the majority of human history, virtually forgotten.
The more you consider it, the harder it is not to find that a little unsettling. Our digital world appears to float somewhere above us, untethered and resilient, according to the popular perception of satellite internet—Elon Musk’s Starlink beaming connectivity from orbit. It doesn’t. The amount of data that cables can handle is far greater than what satellites can. The two biggest private investors in submarine cable infrastructure, Google and Meta, appear to understand this better than most governments, investing heavily in redundant systems and new cable routes to guard against geopolitical chokepoints. They’re not acting philanthropically. The power is located in the cables.
Furthermore, most people are unaware of the variety of risks. Every year, between 150 and 200 cable damage incidents occur worldwide. Most—between 70 and 80 percent, depending on the area—are the result of unintentional human activity, such as ship anchors dropped carelessly in the wrong spot or fishing trawlers dragging nets along the seabed. Most of the time, these situations are controllable. Cables are spliced, repair vessels react, and service is resumed. According to Stephen Holden of the subsea engineering company Global Marine, the global network is “remarkably resilient” considering the amount of damage it sustains each year. That’s most likely accurate. However, the threat profile has changed, and resilience is a relative concept.
A number of incidents in the Baltic Sea in recent years have garnered attention that cable repair crews’ quiet competence could not contain. Cables have been severed, and suspicions have been raised about state-sponsored actors using fishing and oil vessels to intentionally cause damage. These suspicions are not entirely confirmed, but they are also difficult to rule out. The technique is almost elegant in its simplicity: you can cut off a vital communications link between nations without firing a shot by dragging an anchor along the seafloor in the appropriate spot. In certain instances, it is officially unclear whether these incidents were unintentional or deliberate. However, NATO’s response—assembling a flotilla in the Baltic in early 2025—speaks for itself.
The geopolitical honeymoon of the early internet is over, according to two HEC Paris researchers, Olivier Chatain and Jeremy Ghez. As the US, EU, and China pursue divergent ideas of digital sovereignty, what was once shared infrastructure is turning into contested territory. Leverage points, or locations where a disruption could isolate, destabilize, or coerce, are now being considered for the cable routes that once connected the world. The next big geopolitical conflict might not even involve trade tariffs or missiles. A ship, an anchor, and a section of the seafloor that no one is looking at could all be involved.
It’s not easy to protect these cables. Mattress coverings, rock placement, and burial methods can prevent unintentional damage in shallow water. Radar, satellite surveillance, and vessel tracking are examples of monitoring systems that can identify suspicious activity close to cable corridors. However, there aren’t enough repair ships to address significant damage, the ocean is huge, and the cables are lengthy. After a break, a major power cable takes weeks or months to repair, which results in lost energy transmission and mounting expenses. The infrastructure was designed with the assumption of good faith in mind. Finding that world is getting more difficult.
