Ensuring the Resilience of Submarine Cables

By Geoff Huston | Originally published 14 Oct 2026

The global internet relies on a hidden network of undersea filaments. To understand the fragility of this system, we can look at specific geographic vulnerabilities.

Case Study: The Matsu Islands

The Matsu Islands consist of 36 landmasses in the East China Sea, situated near mainland China but administered by Taiwan since 1949. They are part of a group of outlying territories that also includes the Penghu and Kinmen Islands.

Connectivity for Matsu is provided by a few critical links: Taima No.2, Taima No.3, and the upcoming Taima No.4. Because the Taiwan Strait is relatively shallow—averaging $\approx 70\text{m}$—these cables are highly susceptible to maritime accidents, such as anchors or fishing gear snagging the lines.

The impact of this vulnerability is stark:

• 2018–2022: 27 separate cable cuts.
• 2023–2025: 4 major service outages.

Similarly, the Baltic Sea—another shallow region containing a mix of data cables and energy pipelines—has seen 11 disruptions since 2023.

The Global Scale of Risk

The world's telecommunications backbone consists of roughly $1.5\text{M}$ kilometers of cabling across 607 active systems.

If these systems were to fail, satellite technology could potentially could not possibly handle the load. The resulting isolation of certain communities would trigger catastrophic economic and logistical failures.

The Threat Landscape

While nature and accidents are constant risks, modern warfare introduces the threat of intentional sabotage.

Historical Precedent: On August 4, 1914, shortly after the UK declared war on Germany, the HMTS Alert used grappling hooks to sever five German cables. This forced Germany to use wireless radio, which the British intercepted, leading to the discovery of the Zimmermann Telegram. A similar operation occurred in September 1939, targeting cables to New York and Lisbon.

Engineering for Protection

To mitigate these risks, engineers employ different construction methods based on the environment.

Landing Stations and Zoning

The point where the cable hits land is a critical vulnerability. Ideal landing stations are:

1. Located in areas with low maritime traffic.
2. Situated where the seafloor drops off steeply to reduce the length of the cable in shallow water.
3. Secured facilities with redundant power.

Administrative Safeguards:

• Establish "Cable Protection Zones" (CPZs).
• Warn vessel operators against anchoring/fishing in specific coordinates.
• Coordinate with international maritime authorities.

Strategic Cable Routing

Designing a route is a balancing act of competing priorities.

• Cost & Latency: Shorter routes reduce capital expenditure and signal delay.
• Geology: Avoiding tectonic plate boundaries and rifts is essential to prevent seismic breaks.
• Security vs. Repair: Deep-sea placement protects cables from ships and spies, but makes it significantly harder to locate and retrieve a broken segment for repair.

The Danger of "Choke Points"

Certain narrow waterways act as bottlenecks for global data. The Bab al-Mandab Strait is a prime example, serving as a conduit for 16 different cables.

In September 2025, severances in this strait disrupted roughly $25\%$ of the total capacity linking Asia, Europe, and the Middle East. Because these waters are controlled by Houthi forces, they remain effectively ungovernable for cable protection efforts.

Summary of Global Choke Points

{
  "critical_zones": [
    {
      "location": "Bab al-Mandab Strait",
      "cable_count": 16,
      "risk_level": "High",
      "primary_threat": "Political/Conflict"
    },
    {
      "location": "Singapore Strait",
      "cable_count": "High",
      "risk_level": "Medium",
      "primary_threat": "Shipping Traffic"
    },
    {
      "location": "Luzon Strait",
      "cable_count": "High",
      "risk_level": "Medium",
      "primary_threat": "Geological/Shipping"
    }
  ]
}