The physical internet: how submarine cables carry your packets
Your packets cross oceans on glass. A look at where the new cables land, who pays for them, and what happens when an anchor wins.
It is easy to forget the internet has a body. Several hundred submarine cables (fibre bundles the width of a garden hose in deep water) carry effectively all intercontinental traffic. Satellites, for all their headlines, remain a rounding error. TeleGeography measured international internet bandwidth growing 23% in 2026, to about 2,259 Tbps: growth has levelled off from the boom years, but capacity has still more than doubled since 2022.
Who is building, and where
The buyers have changed. A generation ago, telecom consortia built cables and sold capacity; today the hyperscalers (the same handful of content and cloud companies from our IPv6 article) build private cables to connect their own data centres. The new routes tell a story too: fresh landings across Africa and southern Asia, and cautious new paths avoiding chokepoints like the Red Sea, where a single anchor-drag incident in 2024 cut multiple cables at once.
Repair remains gloriously physical: a ship grapples the broken cable off the seabed, hauls it up, splices glass by hand, and lowers it back. Two weeks, weather permitting.
Tracing the physical path
Run a traceroute to another continent and watch the latency jump 60–80 ms in a single hop: that is the ocean. Pair this article with the CLI toolkit lesson and you can point at the exact line in the output where your packet got wet.
Why this matters if you’re learning networking: Latency questions stop being abstract once you can name the physical path. “Why is ping to Singapore 180 ms” has a geographic answer, and interviewers enjoy candidates who reach for it.
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