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Global Governance of the Oceans

Seafloor data cables: growth, patterns and uses

  • 3 things to know
  • Component 2

Overview

The cables that carry almost all intercontinental internet traffic: where they run, who lays and owns them, and why a physical line on the ocean floor still beats satellite for capacity.

What you need to know

Answer each one before you reveal it.

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Key term

What share of international data travels by submarine cable?

Numbers

How many submarine cable systems are in service?

Numbers

When was a transatlantic telegraph cable first laid successfully?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What share of international data travels by submarine cable?

    Model answer

    Around 99% of international data traffic travels through submarine cables. Satellites carry only a small remainder.

  2. 2

    How many submarine cable systems are in service?

    Model answer

    Roughly 550 to 600 submarine cable systems are in service worldwide. Together they run to about 1.4 million km.

  3. 3

    When was a transatlantic telegraph cable first laid successfully?

    Model answer

    A working transatlantic telegraph cable was completed in 1866 by the ship Great Eastern. Messages between Britain and North America fell from days to minutes.

  4. 4

    What was TAT-1?

    Model answer

    TAT-1 was the first transatlantic telephone cable, opened in 1956. The system carried only 36 simultaneous calls.

  5. 5

    When did fibre-optic cable first cross the Atlantic?

    Model answer

    TAT-8, the first fibre-optic transatlantic cable, entered service in 1988. Capacity rose by orders of magnitude over the copper systems it replaced.

  6. 6

    Why are cables preferred to satellites for carrying data?

    Model answer

    Fibre carries far more data at far lower cost for each bit. Latency is also much lower than on a geostationary satellite link.

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