Google and Facebook lay thousands of miles of undersea cables to ferry internet around the world. Here's how they do it.

Isobel Asher HamiltonSep 19, 2021, 15:05 IST

Specialised vessels like this one are used to lay thousands of miles of internet cable along the seafloor.Alcatel submarine networks

Google and Facebook are invested in dozens of subsea internet cable projects around the world.
Laying these cables takes months of preparation, and specialized vessels take them out to sea.
Once laid, the cables can ferry huge quantities of internet data around the globe.

Google and Facebook have both laid thousands of miles of cables along the seafloor, stretching between continents, to carry internet around the world.

An undersea cable laying vessel sails past icebergs during a project to lay cable between Canada, Greenland, and Iceland. Alcatel submarine networks

Often, the two tech giants invest in cable projects along with a consortium of other companies, although Google has five privately owned cable projects underway.

The landing buoy for Google's Curie undersea cable. Google Cloud

Facebook is invested in two cables that are currently active. It is involved in five more cable projects currently under construction, a spokesman said.

Cable laying vessel Ile de Bréhat off the coast of Australia. Alcatel submarine networks

Here's how the companies lay the cables along the bottom of the ocean.

The new Grace Hopper cable will join existing Google cables like Curie, pictured here. Google

First, the companies have to plan the route they want the cable to take.

Jayne Stowell. Google Cloud

A Facebook spokesperson told Insider it conducts a bathymetric and geophysical survey along its expected route, which allows it to plan down to the meter.

Laying vessels Ile d'Aiz (in the foreground) and Ile de Batz (in the background). Alcatel submarine networks

The cable itself is about the thickness of a garden hose, Stowell said.

A subsea internet cable is loaded onto a laying vessel. Alcatel submarine networks

Cables are wrapped in a copper casing for electricity conduction.

Subsea cables in the process of being manufactured. Alcatel submarine networks

For Facebook's 2Africa cable, it's using aluminium rather than copper, which it said will lower manufacturing costs and enable longer cables.

A subsea cable before it's had its sheathing added. Alcaltel submarine neworks

Once the route is mapped out and the cable is made, it's time to load the cable onto a specialised laying vessel.

Crew members spooling Google's Curie subsea cable into tanks inside the laying vessel. Google Cloud

Facebook said its vessels generally need a crew of 30 to 50 people.

A specialised subsea laying vessel. Alcatel submarine networks

The vessel leaves port, spooling the cable behind it. Once it gets into deeper water, it deploys an underwater plow to dig a trench along the seabed into which it lays the cable.

Machinery on a subsea internet cable vessel. Alcatel submarine networks

The vessel leaves port, spooling the cable behind it. Once it gets into deeper water, it deploys an underwater plow to dig a trench along the seabed into which it lays the cable.

"An ocean plough does not look too different from a plow a farmer might use in a field, except it is much larger - about the height of a two-story building," Stowell said.

A subsea laying vessel in the Greenland sea. Alcatel submarine networks

"An ocean plough does not look too different from a plow a farmer might use in a field, except it is much larger - about the height of a two-story building," Stowell said.

"This is where it is needed to protect the cable from potential damage from other seabed users - most frequently bottom trawling fishing vessels or ships anchors that are put down at sea in a storm," Stowell said.

Subsea cables need to be buried to protect them trawler nets like this one. Sylvain Lefevre/Getty Images

"This is where it is needed to protect the cable from potential damage from other seabed users - most frequently bottom trawling fishing vessels or ships anchors that are put down at sea in a storm," Stowell said.

For longer cables, Stowell said Google also installs a device called an amplifier every 100 meters (328 feet) to boost the signal and keep the data moving.

An amplifier is loaded onto a laying vessel. Google Cloud

"Although fibre-optic cables are made of the purest glass, over long distances the intensity of a beam of light begins to weaken," she said.

Subsea cable amplifiers after being manufactured. Alcatel submarine networks

When the laying vessel reaches its final destination it isn't able to come close to shore.

Engineers land Google's Grace Hopper cable on the beach in Bude, UK. Google Cloud

Buoys are used to float the cable at the surface and it is guided into position by divers, jet skis, and smaller boats.

A line of buoys helps float a subsea internet cable as it's landed on the shore. Alcatel submarine networks

Finally, the cable is pulled up onto the beach to a ready-made trench, where it's connected to a beach manhole, a buried container where the undersea cable is hooked up to a terrestrial cable - which in turn connects to a cable station.

A machine helps land Google's Grace Hopper cable on the coast of the UK. Google Cloud

Finally, the cable is pulled up onto the beach to a ready-made trench, where it's connected to a beach manhole, a buried container where the undersea cable is hooked up to a terrestrial cable - which in turn connects to a cable station.

These cables are able to channel a huge amount of data around every second.

Small boats guide Google's Grace Hopper to shore from its laying vessel in Bilbao, Spain. Google Cloud

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Google and Facebook lay thousands of miles of undersea cables to ferry internet around the world. Here's how they do it.

Google and Facebook have both laid thousands of miles of cables along the seafloor, stretching between continents, to carry internet around the world.

Often, the two tech giants invest in cable projects along with a consortium of other companies, although Google has five privately owned cable projects underway.

Facebook is invested in two cables that are currently active. It is involved in five more cable projects currently under construction, a spokesman said.

Here's how the companies lay the cables along the bottom of the ocean.

First, the companies have to plan the route they want the cable to take.

A Facebook spokesperson told Insider it conducts a bathymetric and geophysical survey along its expected route, which allows it to plan down to the meter.

The cable itself is about the thickness of a garden hose, Stowell said.

Cables are wrapped in a copper casing for electricity conduction.

For Facebook's 2Africa cable, it's using aluminium rather than copper, which it said will lower manufacturing costs and enable longer cables.

Once the route is mapped out and the cable is made, it's time to load the cable onto a specialised laying vessel.

Facebook said its vessels generally need a crew of 30 to 50 people.

The vessel leaves port, spooling the cable behind it. Once it gets into deeper water, it deploys an underwater plow to dig a trench along the seabed into which it lays the cable.

"An ocean plough does not look too different from a plow a farmer might use in a field, except it is much larger - about the height of a two-story building," Stowell said.

"This is where it is needed to protect the cable from potential damage from other seabed users - most frequently bottom trawling fishing vessels or ships anchors that are put down at sea in a storm," Stowell said.

For longer cables, Stowell said Google also installs a device called an amplifier every 100 meters (328 feet) to boost the signal and keep the data moving.

"Although fibre-optic cables are made of the purest glass, over long distances the intensity of a beam of light begins to weaken," she said.

When the laying vessel reaches its final destination it isn't able to come close to shore.

Buoys are used to float the cable at the surface and it is guided into position by divers, jet skis, and smaller boats.

Finally, the cable is pulled up onto the beach to a ready-made trench, where it's connected to a beach manhole, a buried container where the undersea cable is hooked up to a terrestrial cable - which in turn connects to a cable station.

These cables are able to channel a huge amount of data around every second.