Dubbed MAREA—Spanish for “tide”—this giant underwater cable will stretch from Virginia to Bilbao, Spain, shuttling digital data across 6,600 kilometers of ocean. Providing up to 160 terabits per second of bandwidth—about 16 million times the bandwidth of your home Internet connection—it will allow the two tech titans to more efficiently move enormous amounts of information between the many computer data centers and network hubs that underpin their popular online services.

“If you look at the cable systems across the Atlantic, a majority land in the Northeast somewhere,” says Najam Ahmad, Facebook’s vice president of network engineering. “This gives us so many more options.”The project expands the increasingly enormous computer networks now being built by the giants of the Internet as they assume a role traditionally played by telecom companies. Google has invested in two undersea cables that stretch from the West Coast of the United States to Japan, another that connects the US and Brazil, and a network of cables that connect various parts of Asia. Rather than just leasing bandwidth on undersea cables and terrestrial connections operated by telecoms, the likes of Google, Facebook, and Microsoft are building their own networking infrastructure both on land and across the seas.

The fact that these Internet giants are laying their own cables—at their own expense—shows just how much data these giants must move. Consider the services they run: Google offers its eponymous search engine, Gmail, Google Docs, Google Maps, and so many more. Microsoft offers Bing, Office365, and its Azure cloud services. Facebook has its social network along with Facebook Messenger, WhatsApp, and Instagram. The data moved by just a few online giants now dwarfs that of most others, so much so that, according to telecommunications research firm Telegeography, more than two thirds of the digital data moving across the Atlantic is traveling on private networks—namely networks operated by the likes of Google, Microsoft, and Facebook. That’s up from 10 percent just a few years ago. “It’s a tremendous change,” says Telegeography analyst Tim Stronge.With so much data flowing across their systems, these companies are scrambling to build new infrastructure. In addition to building its own undersea cable, Facebook is buying up what’s called “dark fiber”—unused terrestrial cables—so that it can control how its data moves from place to place and move it more efficiently. According to Ahmad, Facebook is now using dark fiber “pretty much everywhere” as the company expands its network into new regions. And the same likely goes for Google and Microsoft.

“We’re starting to see more of the large Internet content providers looking to build more of their own networks—whether they are leasing dark fiber or laying down new cables to build new routes,” says Michael Murphy, president and CEO of telecom consultancy NEF. “It makes sense.”

Going It Alone(ish

In the past, Facebook has joined consortia that operate other undersea cables—groups typically made up of telecom companies—but this project is different. Rather than letting a group build and control the cable—that is, rather than sharing lines with others—the company is laying its own dedicated lines and it has the power to use them however it sees fit. In the end, this allows Facebook to expand its online empire much quicker than in the past. “The consortium model is much slower than what we would like,” Ahmad says.Much the same applies to Microsoft. That said, the two Internet giants aren’t abandoning the telecom industry altogether. The pair have brought in another partner: Telxius, a subsidiary of Spanish telecom Telefónica. Telxius will operate the cable, and Facebook and Microsoft services will command most of its bandwidth. But Telxius will sell some capacity to other companies in need of trans-Atlantic connections.

The location of the cable also suits the specific needs of Facebook and Microsoft. Myriad undersea cables connect North America with Europe, but they don’t typically originate in Virginia. Even though Northern Virginia has long served as a major hub for Internet data centers, including facilities used by Facebook as well as dedicated data centers built by Microsoft and Amazon, the data itself typically flows through cables anchored in the New York area. With MAREA, Facebook will be able to more efficiently move information not only from facilities in Virginia but from its Facebook-owned and -operated data center in Rutherford County, North Carolina.