Samanth Subramanian on the Undersea Cables That Keep the Internet Alive

What It Covers

Author Samanth Subramanian explains how roughly 550 undersea fiber optic cables carry nearly all global internet traffic, how ownership has shifted from government telecom consortiums to four dominant US tech companies, and why geopolitical tensions between the US and China are fracturing this critical infrastructure into competing parallel systems.

Key Questions Answered

• •Cable ownership concentration: Google, Meta, Amazon, and Microsoft now fund or own portions of two out of every three new undersea cables laid globally. A single transatlantic cable costs approximately $500 million, affordable for these companies but not smaller players, giving them direct control over which countries and populations receive internet access and under what data privacy conditions.
• •Physical vulnerability and redundancy: Roughly 100 undersea cables are severed annually, mostly by ship anchors or fishing trawlers dragging seabeds. The system absorbs this damage because 550 cables cluster heavily along high-traffic corridors like the North Atlantic and Southeast Asia, providing enough parallel capacity that individual cuts rarely produce noticeable outages for end users.
• •Geopolitical choke points: Egypt and the Strait of Hormuz function as critical cable bottlenecks, mirroring their roles in container shipping. A coordinated attack cutting cables at either location would force global internet traffic to reroute constantly, degrading performance worldwide rather than simply disconnecting nearby countries, since data routing does not follow geographic shortest-path logic.
• •US-China cable bifurcation: No direct undersea cable between China and the US has been laid in years due to sanctions on Huawei's cable subsidiary HMN. Traffic now routes through the Philippines or Singapore. Industry insiders warn this trajectory produces redundant parallel cable systems split along geopolitical lines, undermining the open-access architecture the internet was built upon.
• •AI accelerating cable demand: The AI boom reversed a mid-2010s concern about cable oversupply. Training data centers require massive cross-border data flows, creating demand for faster cable deployment. Satellite internet, including Starlink, cannot substitute at scale because aggregate global data appetite, now amplified by AI workloads, grows faster than orbital capacity can realistically expand.