Vox — The Hidden Network of Undersea Cables

A companion page to dt7/Workshop 1 Hardware and Networks. Inspiration video referenced in the Workshop 1 booklet as way2.cc/ca9.

When you watched a YouTube video on a Raspberry Pi during Workshop 1, the data didn't arrive by magic and didn't really arrive by Wi-Fi either. Wi-Fi got the request from the Pi to the classroom router. After that, almost every byte travelled along a real, physical cable — and most of those cables sit on the ocean floor.

Vox shows you the map. Around 99% of the world's internet traffic — every video call, every chat, every cloud save — runs through a network of submarine cables thinner than a garden hose. After this video, "the cloud" stops feeling abstract and starts feeling like a wet tangle of glass.

The Video

About 8 minutes. Vox covers the history (the very first transatlantic cable was 1858 telegraph wire), the modern build (cable ships, repeaters every ~50km, sharks biting fibre), and the geopolitics (who owns these cables, who can tap them).

What to Watch For

The thickness of a real submarine cable — when they show one in cross-section, notice how thin the actual fibre strands are. Most of the cable is armour and insulation against fish, anchors, and seawater.
Repeaters — every ~50–100 km along a cable there's a small box that boosts the signal. Without them, the light pulse fades to nothing before crossing an ocean.
The world map — pause when they show the cable map. Notice how cables cluster: through the Strait of Malacca, around the UK, between the US and Europe. These chokepoints matter for politics and security.
What happens when a cable breaks — boats can find and lift the cable, splice it, drop it back. Wild engineering.
Why "cloud" is a funny word — almost nothing about the internet is actually wireless once it leaves your local network. The metaphor is misleading.

Have a Go

Your turn! Grab a pen and have a crack at these.

Question ① — In your own words, why do submarine cables need repeaters every 50–100 km?

Question ② — Look at a world map (or the one in the video). If you sent a message from Hamilton, VIC to a friend in London, list the major bodies of water it would probably cross under.

⚡ Hint: It depends on the cable route — some go via the Pacific and the US, others via the Indian Ocean and the Mediterranean.

Question ③ — Why does Vox say undersea cables matter for politics and security, not just engineering? Give one specific example from the video.

Question ④ — When someone says they "stored their photo in the cloud", they usually mean they saved it to a server in another country. Trace the rough physical journey of one photo from your phone to a Google data centre. (Wi-Fi → router → ISP → … → cable → … → data centre.)

Last updated: April 2026.

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