Submarine Cables: Heart of The Internet

Submarine cables and their landing points

Today more than half of the world population uses the internet in some form or another. You also have access to the internet otherwise, you won’t be reading this article. This site’s servers are located in the US, and you might be from some other part of the world but still have access to this site. Ever wondered how is this possible? That’s due to submarine cables, which we are going to discuss in this post. But before that, you should know what the internet is?

What is internet?

The internet is a vast global network of many smaller networks. These smaller networks are called as Autonomous Networks (or Autonomous Systems). These autonomous networks have their own policies on how they operate within the network (i.e. don’t need an approval from a centralized authority hence the word autonomous). Autonomous networks are generally located within a geographical boundary (a country for example). Many times these autonomous networks are physically separated by water bodies (seas and oceans). So, how to connect these networks separated by oceans? This is where submarine cables come into play.

What is a Submarine Cable?

Cross section of a modern submarine cable using Optical Fiber technology, Source: Wikipedia

Cross section of a modern submarine cable using Optical Fiber technology, Source: Wikipedia

1 – Polyethylene
2 – Mylar tape
3 – Stranded steel wires
4 – Aluminium water barrier
5 – Polycarbonate
6 – Copper or aluminium tube
7 – Petroleum jelly
8 – Optical fibers

Submarine cable is a cable which is laid on the seabed (or ocean floor) and is mainly used for carrying telecommunication signals (cables which carry electricity also exist). Modern submarine cables are based on optical fiber technology, as it provides much more speed than previously possible (in 100s TAB/S). It has been in use commercially since 1850s. The first link UK and the USA, which also happen to be the first cross Atlantic submarine cable was finished in 1858 (although it functioned only for a month). These days ships especially designed for laying these cables are used (at first they just retrofitted other ships for this purpose).

Why is Submarine Cable needed, why not something else?

As soon as wired communication technology became available, a need for some sort of transmission medium capable of transmitting signals across seas and oceans became necessary. A wireless radio transmission is an option but, it did not exist in the 1860s. Same is the case with satellite communication. A major factor in choosing the transmission medium in telecommunications is speed ( bits/bytes per second), in which the optical fiber submarine cables are way ahead of any other long-range transmission media. That’s why submarine cables are needed.

Interesting facts about submarine cables:

  • By the year 1871, all the continents except Antarctica were connected via submarine cables.
  • In August 1850, the first commercial submarine cable link was established between France and the UK in the English Channel.
  • The first inter-continental link was established between the UK and the USA in 1858.
  • The first inter-continental message to be sent was “Glory to God in the highest; on earth, peace and good will toward men”.
  • Antarctica is the only continent which is still not connected via submarine cable to the rest of the world ( satellite communication is the only way of connecting with the rest of the world).
  • Animation of a submarine cable repair. Source: WikipediaSubmarine cable repair animation

A submarine cable repair ship in action.


This website has an interactive map which shows different submarine cables and their operators, and also other details.

If you like this article then you may also like our article on Internet of Things.

If you like this Please Subscribe

Don’t forget to share.

Aftab Alam

Editor at Verit Nation.

You may also like...

2 Responses

  1. Shrey Garg says:

    Nice content first of all !!
    Second thing i want to ask you is how deep they leave their cables in sea because the oceans are so deep as nobody ever went there and even cost will increase as they allow deeper?

    • admin says:

      The cables are laid on the sea-floor, hence the distance depends on the location they are being laid, as the depth of sea-floor is not constant at all places. There are specialized vessels for the purpose of laying the submarine cables.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.