The idea that saboteurs in wetsuits would dive to the bottom of the Mediterranean Sea and cut a fibre optic cable, though not impossible, is highly unlikely, if only because doing so would be a good way to wind up dead. "These cables are carrying thousands of volts of power," Mark Simpson, CEO of SEACOM, told Wired. The company owns five undersea fibre optic lines running from South and East Africa to Asia and Europe. Attempting to cut such a line could easily kill you, he said, making sabotage "pretty unusual and pretty dangerous."

That's not to say it didn't happen, and so far, it's one of the explanations the Egyptian military has offered in the five days since naval forces arrested three men alleged to have attempted to cut an undersea cable off the coast of Alexandria. The head of Egypt Telecom said the incident caused a 60 percent drop in internet speeds.

The men have insisted they cut the cable by mistake. Egyptian officials haven't offered any further details on what exactly happened to the South East Asia-Middle East-West Europe 4 (SEA-ME-WE 4 for short) cable beyond saying the military stopped a "criminal operation."


Regardless of what exactly happened, the incident underscores the vulnerability of the world's undersea communications cables to damage, intentional or not. Nearly 200 undersea fibre optic cables link the world's telecommunications, and they are for the most part poorly armoured, rarely patrolled and only occasionally monitored.

Telecommunications market research firm TeleGeography recently released an intricate map (ironically, it is sponsored by Telecom Egypt) that traces the routes these cables follow. When a major cable breaks (or gets cut), it can severely slow down internet connection speeds and even put countries completely in the dark.

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A cut cable off the coast of Alexandria in 2008 left Egypt, India, Pakistan and Kuwait in the dark. A 2006 earthquake in Taiwan damaged several cables and cut off communication to Hong Kong, South East Asia and China.

There has been some suggestion that the guys in Alexandria were treasure hunters who thought the cable might contain copper, Simpson said. It wouldn't be the first time someone cut a line trying to strike it rich. Two years ago, a Georgian woman struck a fibre optic cable while digging for copper, cutting off internet access to neighbouring Armenia for five hours.


Historically, however, undersea cables are more susceptible to accidental breakage by ship anchors, fish trawlers and natural disasters. Tim Stronge, a researcher at Telegeography, says such mishaps snap cables about 100 times a year. Some countries try to prevent breakages by providing detailed nautical maps and levying heavy fines for dropping anchor or casting nets in close proximity to cables. "The industry is accustomed to cables breaking," Stronge said. "They are armoured when they are close to shore and generally they are buried slightly under the sea floor closer to the beach."

A single submarine cable is anywhere from 0.75 to 2.5 inches thick. The armored cables closer to shore can have up to two layers of galvanised wires protecting the fiber optic core (.pdf).

These aren't the kind of cables you cut with a pair of wire cutters.

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That said, nothing is impossible, which is why it is somewhat surprising that there is little security in place to protect these vital cables from sabotage or terrorism. "Other than obscurity and a few feet of sand, [the cables] are just there," Andrew Blum, author of Tubes: A Journey to the Center of the Internet, told Wired. "The staff at a cable landing station might patrol the path to the beach landing once or twice a day, but otherwise I've never heard of or seen any constant security."

A lack of security can leave cables vulnerable to attack. Some telecoms and governments use radar tracking systems to monitor the area around these cables. Such technology detects when a ship is getting dangerously close to a cable and can warn the vessel of its proximity. But Blum says this high level of awareness can be "a boon to saboteurs" seeking the exact location of certain cables.

In places like Egypt, undersea cables are especially vulnerable because there is a bottleneck of 14 cables coming out of both Alexandria and Cairo. Eight of them connect to the shores of Alexandria. Cutting cables in this area would have a domino effect that would hurt connectivity in many countries. "What's true for shipping is true for the internet," Blum noted.

Cutting these cables would effectively slow down internet speeds in more than just Egypt. A ship anchor recently damaged six cables off the coast of Alexandria in February and led to outages in several East African countries. With so much of the continent's connectivity tied to such a small area, it would make it an appealing target for would-be saboteurs.


That said, terrorist attacks and intentional cable cuttings are rare. Stronge has not heard of another case like that alleged to have happened in Egypt, and said whatever happened remains a matter of speculation. "As far as I know, it hasn't been proven that these men were cutting cables," Stronge said. "It could be a case of these men being in the wrong place at the wrong time. It could be Egyptian authorities being nervous about internet outages."

Stronge said that his biggest fear is that this incident become undersea cable folklore, much like that old saw about sharks biting through the first submarine fiber optic cable. "You still hear that today," he said. "What really happened was the cable was mislaid and it was too taut between the mountains and valleys of the ocean floor. It had nothing to do with sharks. I worry that people will now just assume that there are saboteurs across the coast of Alexandria."

This story originally appeared on Wired.com