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Clouds connected by cables, wet and dry

Tech Talk


February 15, 2020

Greg Cunningham

The internet. Billions and billions of devices loosely connected by copper wires, fiber optic cables, satellites, microwaves and radio frequency networks. All these devices, whether doorbells, smartphones, thermostats, desktop computers, security cameras, laptops, streaming devices or tablets, send and receive digital information through these networks. We know about wires in our neighborhood, WiFi routers and modems where we live and work and cell phone towers. We may even know that the term "the cloud" refers to a bunch of computers in a data center located somewhere in the world.

It's that "somewhere in the world" part that the cables get wet.

When you search the internet for rare 1920s Slovenian baseball cards, or whatever you're searching for, the results of your search will likely have to cross an ocean on an undersea cable.

Even with a thousand communications satellites flying around in orbit, the humble cable is still the champ at moving data. Almost 750,000 miles of undersea communications cables connect the continents. The first trans-Atlantic undersea cable was completed in, are you ready for it? 1858. Back then, Queen Victoria sent a message to President James Buchanan that took 16 hours to transmit. Our technology and our cables are faster now.

Originally, undersea cables were installed, or "laid," by the big telecommunications companies for overseas telephone calls. Lately, the big tech companies are investing in and laying new undersea cables. Google, Facebook, Microsoft and Amazon have either fully funded or invested in undersea cables to connect their data centers in North America, South America, Asia, Europe and Africa. Google, Facebook, Microsoft and Amazon currently own or lease more than half of the total bandwidth available in the undersea cable network.

Planning for a new undersea cable can take up to a year. Undersea cables need to run across flat surfaces of the ocean floor and avoid coral reefs, sunken ships, fish beds and other ecological habitats, and geological obstructions. In shallow water and near coastlines, we bury undersea cables using high-pressure water jets or honest-to-goodness plows.

Each undersea cable has to be custom-built for its destination. All undersea cables are fiber optic now and start as bundles of glass strands, then plastic, steel and tar are added to protect the glass under water. Copper wires are added to power the repeaters sending the signal along the cable. A cable destined for use 8,000 feet under the water is about as thick as a garden hose, while cables nearer to shore might be as big around as an aluminum drink can.

Specialized ships, called cable-layers, spool out the undersea cable across the ocean at about six miles an hour. It's a long, and I would imagine boring voyage, taking months to lay those thousands of miles of cable.

Once they're in place, the cables must withstand heavy currents, rockslides, earthquakes and interference from fishing trawlers. And sharks. No one knows why, but in some places, sharks seem to be attracted to the cables and chew on them. So now, companies are experimenting with shark-proof wrappers for undersea cables. Even with the perils of shark attacks, boat anchors, trawling by fishing vessels and natural disasters, the cables are built to last 25 years.

When an undersea cable breaks, is chewed up by sharks, or torn up by a ships' anchor, how is it repaired? Specially outfitted undersea cable repair ships head out to sea and locate the break (or chew.) If the break is in shallow water, uncrewed vehicles deploy to grab the cable and bring it up to surface for repair. In deep water, the ships lower grapnels to grab onto the cable and bring it to the surface for repair.

There are just under 300 undersea cables connecting the Earth's continents. Some cables are "dark," meaning they haven't been put into use yet, which is a good thing because global data consumption is increasing. In 2013, global internet traffic was about five gigabytes per person; by 2018, it was 14 gigabytes. New techniques in squashing information before sending it down the fiber optic cables and the availability of dark fiber means we have enough undersea capacity for now.

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Do you have a computer or technology question? Greg Cunningham has been providing Tehachapi with on-site PC and network services since 2007. Email Greg at


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