Deep-Sea Submarine Internet Cables

Ownership, Technical Foundations, and Geopolitical & Defence Risks

What They Are and How They Work

Core technology.
Modern submarine cables are bundles of glass fibre strands that carry data as laser light pulses. Repeaters (optical amplifiers) spaced roughly every 50–100 km refresh the signal, letting it cross whole oceans. Multiple protective layers—polyethylene, steel armouring, copper conductors, waterproof Mylar, and sometimes Kevlar—shield the fibres. In shallow coastal waters the cable is usually ploughed a metre or two under the seabed; in the deep ocean it lies directly on the floor.

Scale and performance.

• More than 600 active or planned systems stretch over 1.4 million km.

• Trans-oceanic “super-systems” now offer design capacities of 100–250 terabits per second.

• Optical latency is about two-thirds the speed of light, so a Virginia-to-Spain packet arrives in ~60 ms.

• Cables are engineered for 25-year lifespans, though upgrades to terminal equipment can keep bandwidth modern without relaying new fibre.

Failure patterns.
Around 150–200 faults occur worldwide each year. — 70 % are accidental cuts by fishing trawlers or ship anchors in shallow water; ~10–15 % stem from natural hazards such as earthquakes or undersea landslides; the remainder involve equipment failure, landslides, or (much more rarely) deliberate tampering. Redundant routing means most users experience little disruption unless several cables in the same corridor break at once.

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Who Owns and Operates Them

The shift from telecom consortia to “content providers”

Until the late 1990s, nearly every cable was funded by a club of national telecom carriers (often state-owned) that each bought an indefeasible right of use. Over the past decade, hyperscale cloud and social-media companies—Google, Meta, Microsoft, Amazon—have become the biggest investors. They want to link their own data-centre regions, reduce transit costs, and guarantee capacity for video-streaming, cloud services, and AI workloads.

Today these four firms control roughly half of all lit trans-oceanic capacity, while pure government-owned cables make up only about one per cent of total route-kilometres. Most new systems are either:

1. Private / single-sponsor cables (e.g., Google’s “Equiano” Portugal-to-South Africa route or Microsoft/Meta’s “MAREA” across the Atlantic), or

2. Hybrid consortia mixing a big tech sponsor with regional carriers and, occasionally, state-backed operators (e.g., “2Africa”, the 45 000 km loop around the continent, which includes Meta plus Vodafone, China Mobile, Orange, Telecom Egypt, MTN and others).

Snapshot of notable systems

Historical Incidents and Precedent

• World War I: Britain’s very first wartime act was to dispatch a cable ship to cut Germany’s Atlantic telegraph lines, forcing German traffic onto easily intercepted radio circuits.

• Cold War tapping: The U.S. Navy’s “Operation Ivy Bells” covertly attached recording pods to Soviet naval cables on the seabed of the Sea of Okhotsk in the 1970s, harvesting unencrypted radio-telephone traffic for years.

• Accidental mass outages:

  • December 2008—multiple cuts near Alexandria, Egypt slashed bandwidth between Europe and South Asia by up to 70 %.

  • December 2006—a double earthquake off Taiwan severed several East-Asian cables, disrupting regional internet and financial networks for a week.

• Ambiguous sabotage: 2022 saw two fibre pairs in the Norwegian Sea and Baltic mysteriously clipped within weeks; investigators suspected state-backed sabotage but could not definitively attribute.

These episodes demonstrate that cables can be both critical vulnerabilities and deliberate targets in conflict.

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Contemporary Geopolitical & Defence Risks

US–China technology rivalry

• Cabling influence: Washington now pressures allies to bar Chinese suppliers (e.g., ex-Huawei Marine) from cable builds and landing licences, citing espionage concerns.

• Blocked projects: The Pacific Light Cable Network’s planned Hong Kong landing was vetoed by U.S. regulators in 2020; the cable was rerouted to Taiwan and the Philippines.

• Digital bifurcation: Competing Chinese- and US-backed consortia are racing to build parallel Asia–Africa–Europe routes, each trying to keep key landing stations inside friendly territory.

Russia versus NATO/allies

• Russian “oceanographic” ships and deep-submergence vessels regularly patrol over Atlantic and North-Sea cable corridors, mapping routes and—Western militaries fear—pre-positioning for disruption.

• NATO now treats critical seabed infrastructure security as a collective-defence matter. A specialist maritime centre was launched in 2023; the UK and France have commissioned dedicated seabed-monitor vessels and under-ice drones.

• Hybrid tactics: dragging trawler nets or anchors to create “accidental” breaks can produce economic disruption while retaining plausible deniability.

Vulnerability highlights

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Legal and Protective Frameworks

International conventions

• UNCLOS (1982): codifies freedom to lay/maintain cables and obliges states to criminalise willful damage, but offers limited enforcement mechanisms and is silent on espionage.

• 1884 Cable Protection Convention: still in force; empowers warships to board vessels suspected of damaging cables, yet predates fibre optics and cyber concerns.
  Many experts call for updated treaties or a new protocol specifying that large-scale cable sabotage may constitute an armed attack.

Military surveillance & deterrence

• NATO’s Maritime Centre for the Security of Undersea Infrastructure coordinates intelligence, patrol patterns and rapid repair response.

• Several allies are fielding multi-role ocean-surveillance ships with moon-pools and ROVs for under-ice and deep-sea intervention.

• Public statements now warn that deliberate attacks on cables could trigger collective defence.

Industry cooperation

• The International Cable Protection Committee (ICPC) pools route maps, shares best practices with fishing and shipping industries, and liaises with navies.

• Real-time fibre strain sensors and distributed acoustic sensing give owners early warning if a cable is vibrating or moving abnormally.

• Public-private partnerships (e.g., Sparkle–Italian Navy) combine telco monitoring with maritime domain awareness systems.

Redundancy and diversification

• Tech giants and carriers increasingly route new cables through less-crowded basins (e.g., South Atlantic or Arctic) to reduce choke-point risk.

• Terrestrial fibre corridors (e.g., Europe–Asia via the Caucasus) and low-Earth-orbit satellite constellations provide backup, but neither matches the bandwidth or latency of undersea fibre.

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Bottom Line

Submarine cables carry nearly all intercontinental digital traffic and trillions in daily financial flows. While routine breaks are quickly repaired and generally harmless thanks to network redundancy, deliberate multi-cable sabotage at key chokepoints would pose serious economic and security hazards.

Ownership has shifted toward a handful of U.S. cloud–content giants alongside long-standing telecom consortia, heightening questions of control and strategic reliance. Meanwhile, great-power competition—US–China tech rivalry and Russia–NATO tensions—has thrust cable security onto defence agendas.

The response is still a work in progress: legacy treaties are outdated, military surveillance assets remain scarce, and much of the cable footprint is privately controlled. Yet awareness has never been higher. Closer industry–government cooperation, better seabed monitoring, route diversification, and clear deterrence signals are all advancing. Sustaining that momentum will be essential to keep the global internet’s undersea lifelines safe in an era of geopolitical uncertainty.

Photo Credit: DepositPhotos.com