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The world’s underwater cable network that keeps us all connected.

Posted by: Sam Wheeler


We live in a connected world with the majority of our daily transactions dictated by technology, but have you ever stopped to think about how this is possible and how it came about?

You might be surprised to learn that we are surrounded by a spaghetti-work of extensive wires that are found in the coldest depths of our oceans.

Ninety-nine percent of international data is transmitted through these wires at the bottom of the ocean which are hundreds of thousands of miles long.

The idea first came about in 1843 by Samuel Morse and since then, the laying and maintaining of long undersea cables has been routine operation for 159 years.

The first transatlantic communications cable was completed in 1858 and ran between Ireland and Newfoundland.

The first ever message was sent from Queen Victoria to President James Buchanan containing just over 500 letters and took 17 hours and 40 minutes to transmit across the Atlantic; slow by today’s standards but significantly faster than waiting for a ship to do the same distance.

One of the first cables took a total of four years to build; the theory was unwritten, materials dodgy and the transmitting and receiving instruments primitive. The cable lasted for less than a month and it took another 6 years for a second cable to be set up, however it proved that the concept could work and over time a web of telephone cables began to spread underneath the world’s oceans, which later joined the telegraph cables.

Custom built cable ships have been used since 1874 to run the cables, with one of the very first launched by the Siemens brothers. The ships are instantly recognisable with cable sheaves at the bow or stern, over which the cable descends into the sea.

The initial expeditions of the 1850s were dogged with failures, but each time more money was raised and new expeditions set up. There were great costs to lay the cables at over a million dollars each, but equally they had a high return on investment and it led to a boom in cable laying around the world.

By the end of the century there were 10 Atlantic cables, 130,000 miles of cable already laid at the bottom of the sea and 36 cable ships which were regularly laying new lines.

Once an accurate survey was made to establish conditions at the bottom and a safe path found, the repairing of cables became a routine operation. Precision measuring equipment allowed engineers to locate exactly where any breaks were, and could usually be repaired on board the cable ship. The main difference between then and now is that today breakages can be pinpointed with the help of satellite navigation systems.

Cables still prospered when they were challenged by another medium - the radio. By the 1920s speeds had reached up to 400 words per minute across the Atlantic but this was still only for telegraph messages. It was not until the 1950s when amplifiers were put in to carry voices. The first transatlantic telephone call was in 1956 and consisted of two cables one to carry eastbound traffic and the other for westbound. It could carry a total of 36 telephone channels and a call cost £3 for 3 minutes, the equivalent to over £20 a minute in today’s money!

Eventually and fortunately fibre optic cables were invented and this is still the main form of communication we use today. 1988 saw the introduction of TAT-8, the first fibre optic cable to be placed across the Atlantic that could carry up to 40,000 telephone channels.

Cable capacity has increased a lot since then, with unlimited bandwidth available to almost every part of the world at a low cost. But despite the speed and bandwidth upgrades some things still remain the same; they’re still in depths of the ocean, repair is still done by hauling the cables back onto ships, and although the materials have changed for the better the cables still have a conductor in order to carry the signal as well as an insulator to protect the circuits.

TeleGeography now lists an inventory of nearly 350 cables and generally they are quite safe under water with the only potential threats being spies, ship anchors and sharks.

In 2012 two separate shipping incidents severed cables linking East Africa to the Middle East and Europe. The incidents caused major outages in at least nine countries; which just goes to show how reliant we are on being connected! Today’s fibre-optic speeds can reach over 100 petabit x kilometre per second and data travels faster than the speed of light.

The latest versions by Verizon FiOS and Google Fibre are capable of reaching speeds of 500mbps and 1gbps!

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