How A Million Miles Of Undersea Cables Power The Internet — And Now AI

Key Concepts

• Subsea Cables: Undersea communication and power cables that form the backbone of global internet traffic and energy transmission.
• Optical Fibers: Thin strands of glass that transmit data as light pulses, forming the core of modern subsea telecommunication cables.
• Repeaters: Devices installed along subsea cables to reamplify optical signals, counteracting attenuation.
• Landing Stations: Facilities on land where subsea cables connect to terrestrial networks, housing power feeding equipment and signal transmitters/receivers.
• Attenuation: The loss of signal strength as it travels through optical fibers.
• Web Scale Players: Large technology companies (e.g., Google, Meta, Microsoft, Amazon) that are significant investors and users of subsea cable infrastructure.
• Gray Zone Tactics: Covert or deniable actions by state or non-state actors that fall below the threshold of traditional warfare but aim to destabilize or disrupt.
• Distributed Acoustic Sensing (DAS): A technology that uses subsea cables as sensors to detect and track activity in their vicinity.

Subsea Cables: The Unseen Superhighway of the Internet

This report delves into the critical, yet often overlooked, world of subsea cables, which are the backbone of global internet connectivity and facilitate trillions of dollars in daily economic transactions. Over 95% of international internet traffic traverses these cables, many no larger than a garden hose, spanning nearly a million miles globally.

Manufacturing and Technology

The video highlights the manufacturing process at Alcatel Submarine Networks (ASN) in Calais, France, the world's largest manufacturer of these internet arteries.

• Core Components: Modern subsea cables rely on optical fibers that transmit data as light pulses. Dozens of these hair-like fibers are bundled together.
• Signal Amplification: To combat attenuation (signal loss), repeaters are installed every 50 to 62 miles to reamplify the light signal.
• Protection Layers: The delicate optical fibers are encased in a metal tube, followed by layers of copper (for power), plastic, and potentially steel wires for armoring.
  • Lightweight Cable: The basic construction with copper and plastic.
  • Single Armor: An additional layer of steel wires for increased resistance.
  • Double Armor: Two layers of steel wires, typically used in shallower waters near beaches where damage risk is higher due to potential aggression or chafing. Deeper waters may not require such heavy armoring.
• Powering Repeaters: Landing stations are crucial for powering the submerged repeaters, as they do not operate on batteries. These stations also house transmitters and receivers to inject telecom signals into the fiber.
• Manufacturing Scale: ASN has produced 850,000 km of cable, equivalent to approximately 21 times the Earth's circumference.
• Key Manufacturers: The industry is dominated by four major companies: Subcom (US), NEC (Japan), Alcatel (France), and H&M Tech (China).

The Growing Demand and Key Players

The past two decades have witnessed significant growth in subsea cable deployment, driven by a "voracious demand for data." This demand is increasingly fueled by web scale players like Google, Meta, Microsoft, and Amazon, who are investing heavily to support their computation-intensive AI models and expanding data center networks.

• AI's Role: AI necessitates robust connectivity between data centers, making subsea infrastructure essential. Without it, data centers are described as "expensive warehouses."
• Investment Trends: Investment in new subsea cable projects is projected to reach approximately $13 billion between 2025 and 2027, nearly doubling the investment from 2022-2024.
• Major Tech Company Investments:
  • Meta: Investing in over 20 subsea cables, including the nearly complete 28,000-mile, $1 billion 2Africa cable connecting three continents. They are also developing Project Waterworth, a 31,000-mile, multibillion-dollar project spanning five continents.
  • Google: Invested in over 30 subsea cables, including the Sol project connecting the US, Bermuda, the Azores, and Spain.
  • Amazon: Invested in projects like Bifrost, Jako, and Havfrue, and announced Fastnet, its first proprietary cable connecting Maryland to Ireland. Amazon emphasizes that subsea connectivity is essential for AWS, offering lower latency and higher capacity than satellite alternatives.
  • Microsoft: Also actively pursuing new subsea cable projects.
• Market Growth: The market for telecom submarine systems has grown from around $2 billion annually in 2016-2017 to $5-6 billion annually today, partly due to web scale players building their own systems.

Historical Context and Evolution

Subsea cables are not a new technology.

• First Commercial Cable: Laid across the English Channel between Dover and Calais in 1850, made of copper for telegraphy.
• Evolution: From telegraph cables to coaxial cables for telephone conversations, and then to fiber optic cables in the 1980s, enabling internet transmission.
• Power Cables: While the focus is on data cables, high-voltage power cables also cross oceans, typically thicker and used for renewable energy transmission or grid interconnections.

Deployment and Maintenance

The process of deploying and maintaining these vital cables is complex and resource-intensive.

• Deployment: Cables are loaded onto specialized ships at ports like Calais. In shallower waters, a plow towed by the ship buries the cable in the seabed. In deeper waters, the cable is laid directly on the seabed due to lower risk.
• Cable Ships: ASN operates a fleet of seven ships: four for installation, two for maintenance, and one dual-purpose vessel.
• Project Timelines: Completing a cable project can take 2 to 4 years, encompassing route selection, surveying, permitting, manufacturing, and installation.
• Permitting Challenges: Obtaining permits can take 6 to 24 months and is complicated by the number of countries a cable traverses, territorial waters (up to 20km), and economic zones (up to 300km). Geopolitical issues in areas like the Mediterranean (Greece/Turkey disputes), the Red Sea, and the South China Sea can further complicate permitting.
• Maintenance: ASN services over 205,000 miles of cable. However, cable repair has become a bottleneck, with the average repair time reaching 40 days in 2023. The industry is discussing new models to address this strain.

Threats and Security Concerns

Despite their critical importance, subsea cables are increasingly becoming targets of concern, both accidental and potentially intentional.

• Accidental Damage: An estimated 100 to 200 incidents occur annually, with the vast majority being accidental.
  • Fishing Activity: The most prevalent cause, with trawlers operating as deep as 1500 meters. This necessitates armoring and burying cables up to this depth.
  • Anchoring: Anchor dragging is another significant cause.
  • Volcanic Activity: Can also cause disruptions.
• Sabotage and Gray Zone Tactics: There is growing suspicion of sabotage, described as gray zone tactics, where hostile actors can cause damage and claim it was accidental.
  • Recent Investigations: Germany, Sweden, and Finland are investigating damage to cables in the Baltic Sea as sabotage. Taiwan detained a Chinese cargo ship suspected of severing a cable.
  • Security Concerns: The Federal Communications Commission (FCC) in the US has tightened rules for foreign firms building subsea infrastructure, citing security concerns.
  • Adversarial Interest: Foreign adversaries are interested in controlling the information environment, and compromising subsea cables, which carry 99% of global internet traffic, is a potential method.
  • Uptick in Suspected Intentional Damage: Recorded Future has observed an increase in intentional damages in 2024 and 2025, particularly in the Baltic Sea and around Taiwan, though definitively proving intent is difficult.
  • China's Capabilities: Reports of China developing an advanced submarine-mounted device capable of cutting cables at depths of up to 4000m raise concerns.
• Cable Surveillance: Advanced nation-state actors (primarily Russia and China) possess the technology to access cables at deep ocean depths without alerting owners. However, tapping cables for information is currently considered very difficult and low-threat due to the complexity of decryption and data processing.
• Targeting Landing Sites and Software: Bad actors are more likely to target accessible landing sites or exploit software vulnerabilities through cyberattacks.
• Hyperscaler Security Measures: Tech giants assure that data interception risk is low due to multiple redundant cable paths and robust encryption at network, application, and top layers.

Government and Industry Responses

Governments and industry players are taking steps to address these security concerns and ensure the resilience of subsea infrastructure.

• NATO's Baltic Sentry: Launched in response to cable cuts in the Baltic Sea, involving aircraft, drones, and vessels to monitor traffic and deter further incidents.
• Government Investment:
  • France: The French state acquired 80% of ASN, recognizing subsea cables as a strategic asset for France and Europe.
  • US FCC: Implementing measures to prevent direct US cable connections to adversarial nations (e.g., China, Russia), prohibiting "spy gear" like Huawei and ZTE, increasing transparency in cable ownership, and expediting permitting for domestic investment.
• Industry Collaboration:
  • Meta, Amazon, Google, Microsoft: Assured they do not work with PRC-affiliated cable maintenance providers on announced systems and comply with US regulations.
• Technological Advancements:
  • Distributed Acoustic Sensing (DAS): Developed by Amazon, this technology turns subsea cables into passive sonar arrays to detect and track ships, submarines, and other activity near the cable. ASN is working to expand DAS capabilities to full cable lengths. This acts as a "warning system."

Conclusion

Subsea cables are indispensable to modern society, underpinning global communication, commerce, and critical services. While accidental damage remains common, the increasing focus on potential sabotage and the strategic importance of this infrastructure are driving significant investments in security, technological innovation, and governmental oversight. Protecting these "unseen superhighways" is paramount to maintaining global connectivity and economic stability.