Glossary
What Is a Submarine Cable?
Submarine cables are the undersea fibre-optic lines that carry almost all intercontinental internet traffic. Because a handful of cables and their landing stations carry so much, they are a physical single point of dependency — now a focus of the FCC's 2026 cable-security rules and the EU's Cable Security Toolbox.
Why undersea cables matter
The internet feels wireless, but its backbone is glass on the seabed. Submarine cables carry the overwhelming majority of intercontinental data, and a single cable can carry a meaningful share of a region's connectivity. Damage one — by anchor, earthquake, or sabotage — and latency, capacity, and routing shift for everyone who depended on it.
Landing stations as chokepoints
Cables come ashore at landing stations, and those stations cluster. A few coastal sites can concentrate the connectivity of an entire region, making them physical chokepoints whose compromise or failure has outsized effect. Mapping which networks depend on which landings turns an invisible dependency into something you can reason about.
The regulatory turn
Governments now treat cables as critical infrastructure. The FCC's 2026 Second Report and Order tightens submarine-cable security, and the EU's Cable Security Toolbox commits significant funding to resilience. Both push organisations toward understanding their physical-layer dependencies, not just their logical ones.