Exploring the World’s Undersea Cables

Lurking deep in the ocean is a network that’s absolutely essential to life as we know it today. As deep as Mount Everest, amongst rugged sea creatures and frightening darkness, lies a network of undersea (or submarine) cables transmitting data to and from all corners of the Earth.

Amidst talk of cloud computing and virtual networks, it can be easy to forget the fact that today’s newest technologies are still backed by physical infrastructure. Just as two carriers connect to one another in a data center with a physical cable, so too are different parts of the world connected to one another by way of undersea cable.

So: who’s behind this network of submarine cables? How are they laid? Why do we need them? Today, we’re going to explore those questions and examine the fascinating world of undersea cables. We think you’ll find, as we do, that the physical network that connects the world is fascinating once you take a closer look.

The Submarine Cable Map: 321 Cable Systems as of 2016

Submarine Cable Map, courtesy of TeleGeography

Let’s start with the network of cables itself. Just how many submarine cables are there, exactly? According to TeleGeography, a telecommunications market research and consulting firm (and leading voice on undersea cable information), there are 321 cable systems that are currently active, under construction, or expected to be fully-funded as of the end of 2016.

As you can see on TeleGeography's interactive Submarine Cable Map (last updated on March 21, 2016 as of this writing), the current network of cables is impressive, to say the least. Submarine cables currently link all continents except Antarctica. As you can see from the map, there are cables linking the West Coast of the United States to Australia and Southeast Asia, South America to Africa, and the East Coast of the United States to numerous locations across the Atlantic Ocean—just to name a few. It seems you’d have a harder time finding a major location that isn’t linked by submarine cable than you would finding two locations that are connected.

Astute Telx customers will even notice that FASTER, one of the newest additions to the world's submarine cable network links Oregon to two locations in Japan, as well as an additional location in Taiwan:

Image via TeleGeography Submarine Cable Map

Telx announced its support for FASTER last summer as part of its effort to expand its interconnection options. The FASTER cable, nearly 12,000km long, will have an initial capacity of 60 TB per second. And to think—this is only one of more than 300 undersea cables that currently make up the world’s submarine cable network.

Today, it's estimated that submarine cables transmit 99% of all international data. Undersea cables are reliable, fast, and have high carrying capacity, especially compared to their most viable alternative, satellite links. Satellite links are also currently significantly more expensive than undersea cables, making their submarine counterparts much more viable for the vast majority of situations.

As the soon-to-be addition of the FASTER transpacific cable system shows, today's submarine cable network is growing in response to a global uptick in IP traffic. It’s unclear how many more cables will need to be added as consumption increases, but for now, these approximately 300 cable systems are an important part of maintaining the Internet as we know it.

A Brief History of Undersea Cables

If you thought that submarine cables were a relatively recent invention, you’d only be partially correct.

The vast majority of today's submarine cable systems are complex and take advantage of the latest and greatest in fiber optic technology, which wasn’t even developed for commercial use until the last decade or so of the twentieth century. What's more, lit capacity has grown significantly in the last decade; as TeleGeography notes, in the past five years, lit capacity has increased 2.4 times.

This only takes into account modern submarine cables, however. They’re the “relatively recent” part of the “relatively recent invention” we just mentioned. The undersea cable as a more general concept—more specifically, for telegraphs (as opposed to telecom) use—is much older.

Incredibly, the first transatlantic cable was constructed and put into use in 1858. The cable, designed to transmit telegraphs, was relatively short-lived—but it wasn't long until the technology was improved significantly. By the early 1900s, as the map below shows, a complex network of telegraph cables had been constructed.

Carte générale des grandes communications télégraphiques du monde, 1901/03 International Telegraph Bureau, courtesy of Atlantic-Cable

As the above map shows, despite much less advanced technology than is available today, and despite the fact that the cables only transmitted telegraphs, a significant network of undersea cables had already emerged by just 1901! These cables reduced message delivery times from weeks to minutes. Coupled with the sheer number of locations these cables linked, it isn’t hard to see how this network dramatically impacted communication at the time.

Of course, as bandwidth needs grew and as technology evolved, these telegraph cables were slowly replaced with telephone cables and again with fiber optic cables, while at the same time the network itself grew significantly, looping in more and more locations and expanding the reach of global communications.

It wasn’t long until this network grew into the behemoth it is today, albeit with much more advanced technology. Even so, it’s incredible to think that over 150 years ago, technological pioneers were already laying the foundation for today’s advanced network of submarine cables.

The Driving Forces Behind These Tremendous Connections

You now know how big today’s submarine cable network is, and you know how it evolved from humble beginnings as a telegraph network into a high-bandwidth fiber optic behemoth. You may be wondering, however, who’s responsible for funding and constructing these cables.

For much of the early history of telegraphic undersea cables, major construction was funded by telecom companies themselves. Though that trend continued into the early 1900s, with telecommunications companies responsible for their own cable design, manufacturing, and laying, that pattern has shifted towards individual companies each handling the manufacture, permitting, maintenance, and laying of cable separately.

Many cable systems are financed by consortia of companies with common interests in global interconnectivity. This reduces individual financial risk and also increases the amount of capital available for these expensive, time-consuming projects.

The FASTER cable system we've already discussed, for example, is being developed by the FASTER consortium, which is comprised of six parties, including China Mobile International, China Telecom Global, Global Transit, Google, KDDI, and Singtel. As Data Center Knowledge notes, the FASTER cable system will make it more feasible for organizations to expand their IT operations into Asia, and vice versa—hence the joint investment by both Asian and American companies.

Today's undersea cables are incredibly important, and as bandwidth needs increase we can only expect to see investment in submarine cable systems increase as well.

How Cables Are Laid

Aside from the history of submarine cables, perhaps the most interesting element of these cables is how they are laid. As you can imagine, laying an undersea cable isn’t quite as simple as unspooling a cable and throwing it out into the ocean. Plotting a route, building the cable, laying it on the ocean floor, and making it operational takes expertise, lots of planning, and sophisticated technology.

Let's start with the cables themselves:

Photo courtesy of NEC Global

Modern submarine cables are made up of many layers. This specific example is surrounded by a polyethylene cover, with multiple layers of shielding and waterproofing protecting the important central layer of optical fibers. It’s much more robust than, say, an Ethernet cable which would be used to form a cross connect at a data center. The cable does have to survive and transmit data deep in the ocean, after all.

As for the laying of the cable? After the cable is constructed, it starts onboard the cable ship, a proprietary ship which can hold around 2,000km of cable and which has a plough to lay cable safely in a trench. In an overview of the process, The Independent notes that the ship begins its journey when a long cable section is connected to the landing point (at a landing station) and then extended a few miles out into the sea. At that point, the cable-laying ship uses its plough to carefully lay the cable into a trench. Newer ships can do about 200km of cable laying per day.

Many modern cables are laid along similar routes to their telegraphic cable ancestors, but plotting new routes is still possible, if more time-consuming. All-told, laying submarine cable is such an expensive and time-consuming process because it requires proprietary equipment that's been perfected over time. Snags in the process can require expensive repairs.

Companies may have been building this network and improving processes for a while now, but no matter what, they’re still dealing with a harsh environment and with infrastructure which must be robust. All this investment and hard work pays off when customers are treated to a robust, reliable interconnection point between two locations which would otherwise remain separate.

Plotting the Future

Submarine cables are viewed as a tremendous feat of engineering, and for good reason—they’re used every day to transmit data to all corners of the globe. Often utilized but infrequently discussed, they’re an important asset and contribute significantly to the network that makes the world tick today.

With the world’s bandwidth needs growing every day, the world’s complex network of submarine cable systems will likely only continue to grow over time. The next time you access an international website or send an email to a business partner overseas, you’ll know exactly how much technology went into helping transmit that message.

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