Why submarine cables play a crucial part in our everyday lives


September 30, 2020

On August 16th, 1858 international communications changed forever when Queen Victoria sent a short message in the form of a telegram to the then US president James Buchanan. The message travelled through 2,500 kilometres of newly laid submarine cable and took 16 hours to arrive. But it worked and was a massive improvement on the alternative 10-day duration it would have taken to cross the Atlantic by sea. In 1866, it cost the equivalent of $30 to send a 20-word telegram – a third of the annual salary of a fisherman in Newfoundland where the Atlantic Cable landed, so the initial take up and growth of subsea cables was limited.

Today, with the growth and importance of global voice and data communications, submarine cables are of crucial part of our everyday lives and typically are owned by multiple companies, many of them telecom operators in strategic locations. In recent years big tech companies such as Amazon, Google and Facebook have joined in the market and made considerable investments in new cable projects.

Laying a cable is a years-long process which costs millions of dollars. Once the route is plotted and checked, and the shore connections are secure, huge cable laying ships which can hold up to 2000km of cable begin the long and tedious process of laying and splicing together cables. The process is more than just throwing cable into the sea, care must be taken to ensure the route is safe from currents, seismic events and other interference that could damage the cable. Typically, cable systems are designed for a 25-year life span, but there may be instances when parts may need repair so it’s important that the cable remains accessible if that need arises.

Though it may come as a surprise to many people, most of our internet communication still involves submarine cables today. Even though there are thousands of satellites now orbiting the earth, it’s still necessary to run very long cables along ocean floors. New technology has in this case not overtaken the old. In fact, as little as 3% of global communications are carried via satellite, which means 97% of the world’s communications are transported around the world via fibre optic submarine cables. Anyone old enough to have watched TV in the 80s would have heard the “and now … transmitted by Satellite!” announcements from proud channels presenting cross-Atlantic events. The problem is that satellite transmissions suffer from latency and loss whilst optical fibre can transmit at 99.7% of the speed of light. This gives cables a significant advantage over satellite when speed and cost are critical such as in the world of international commodity and share trading where fractions of a second could make the difference between profit and loss.

Today there are over 400 submarine cables in service around the world, and 1.2 million km of cable. One such major new cable system is the PEACE (Pakistan & East Africa Connecting Europe) cable project. When complete it will be over 15,000km long, adopting the latest 200G technology which provides the capability to transmit over 16Tbits/s per fibre pair. PCCW Global is a proud part of the project consortium. The cable will provide the lowest latency, shortest route connectivity between Asia, Africa and Europe.

Sea cables