Technology: The low-down on undersea internet cables.

Where does the internet come from? Is it from satellites beaming connectivity down from the sky? For the most part, when data moves between countries, it’s thanks to undersea cables.

DOWN TO THE WIRE

THE INTERNET IS a physical network connected on land and under the ocean by around 380 undersea cables worldwide that form the backbone of the internet. The more than 1.2 million km of submarine cables span entire oceans and take years to plan and build, and just as long to install. Undersea cables are phenomenal pieces of networking infrastructure. They require state-of-the-art technology that combines the best engineering minds, advanced physics experts and marine biologists. Each cable has to be built for purpose, and the stretch of ocean it spans as well as where it lands on shore must be taken into account.

The standard design of fibre consists of send-and-receive components – two fibre pairs within a urethane strand. Subsea cables are limited to 16 fibre pairs but on land terrestrial cables can have 244 fibre pairs and more can be added if needed. The fibre-optic strands are the width of a human hair and coated in gel to keep them in place inside a plastic tube, which is covered with steel wires, copper and plastic for insulation.

Surrounding the African continent, there is both the EASSy Cable System and WACS, but it was SEACOM that launched Africa’s

first broadband submarine cable system back in 2009. Google is in the process of building Equiano, a new Google-owned subsea cable (their third) that will connect Africa with Europe – the first phase of the project, connecting South Africa with Portugal, is expected to be completed in 2021.

And there are even more cables coming…

SEACOM engineers on a cable-laying shift, splicing fibre together.

Submarine cables are stored in the ship’s hull. As the ship moves, the cable gets laid.

Above: The crew aboard a cable-laying ship feeding a subsea cable into the burial plough.