At The Bottom or What Threatens Underwater Internet Cables


At The Bottom or What Threatens Underwater Internet Cables

Virtually all communication on the planet is provided by means of cables that are stretched between states and continents. As of the beginning of 2017, there were 428 cables in the world under water, with a total length of 1.1 million kilometers.

  • All of them have different capacity. The record holder for this indicator is the Marea cable between Virginia and Bilbao (160 Tb/s). According to various sources, submarine cables transmit about 95-99% of all data.

But they are regularly damaged. This was encountered in the XIX century when laying telegraph cables. The first cable laid in Munich along the Isar River had insufficient waterproofing, so it quickly broke down.

  • In 1858, laid the first telegraph cable through the Atlantic Ocean. It failed in less than a month, due to the fact that the operators were applying too much voltage to it in order to increase the data transfer speed.

The current cables are more reliable, but they also require repair. In our material, we will tell you what threatens them most often.


65-75% of the breakdowns of submarine cables is due to transport and fishing vessels – they drop anchors that fall into the cable. On January 30, 2008, the cable SEA-ME-WE 4, which stretches from France along Africa to Southeast Asia, thus failed. A breakdown in a stretch of the Mediterranean has resulted in a decrease in traffic by 70% in Egypt and 60% in India. The incident also affected Afghanistan, Bahrain, Kuwait, Maldives, Pakistan, Qatar, Saudi Arabia and the United Arab Emirates. Restore communication on other cables was a day later.


Interestingly, in December of the same year, SEA-ME-WE 4 cable, along with SEA-ME-WE 3 and FLAG Telecom, again failed. Before the elimination of breakdowns from the countries of Asia and the Middle East, the rest of the world was 75% less traffic than usual.

  • In 2012, the ship dropped anchor in the wrong place, waiting for permission to enter the Kenyan port of Mombasa. As a result, the fiber optic cable was cut, and residents of six African countries encountered communication problems. The Internet has become 20% slower, and it cost the Kenyan economy 300 million pounds.
  • And in 2016, one vessel damaged just three cables connecting the island of Jersey in the English Channel with London.

Captains of ships are aware of areas where you can not drop anchor because of the possibility of damaging the underwater cable. The more surprising are such mistakes in the cases described above.

Natural Disasters

Various natural phenomena – the causes of 10% of breakage of submarine cables. In 2006, due to the earthquake in the region of Taiwan, 8 cables failed at once. This led to a significant reduction in traffic in the Asian region and the disruption of Internet services.

Chunghwa Telecom, the largest telecom operator in Taiwan, said that for a while there was no connection with Hong Kong and Southeast Asia, and the PRC received 74% less traffic. The largest operator of Hong Kong PCCW announced a decrease in traffic by 50%. Two Chinese operators: China Telecom and China Unicom reported a 90% drop in traffic to the US and Europe, which did not work for Yahoo, MSN, and Hotmail.

At the end of August 2017 two typhoons passed in Asia: “Hato” and “Pahar”. Because of them, the four cables that connect Hong Kong to Japan, the Philippines, Malaysia, Singapore and the United States have been damaged. The operators temporarily redistributed traffic through other cables.


People are another reason for frequent breakdowns. For example, in 2013, Egyptian authorities detained three people who cut the cable SEA-ME-WE 4 on a site in the Mediterranean Sea near Alexandria.

According to the head of Egypt Telecom, as a result of the incident, the Internet speed in the country fell by 60%. At other times, traffic would simply go by other cables, but it was at this point that the alternative EIG and IMEWE were on maintenance.

And the human factor does not bypass the ordinary underground cables. In 2011, a 75-year-old Georgian woman was looking for copper near the village of Ksani and accidentally cut the fiber optic cable. As a result, most of Georgia and neighboring Armenia stayed for several hours without the Internet.

Sharks Are Not That Scary

Often among the main dangers for underwater cables are called fish. On the Internet, there is even a video on which a shark tries to gnaw a cable.

But in fact, the danger is exaggerated. According to the ICPC (International Cable Protection Committee) statistics, fish are “responsible” in less than 1% of the damage. Also, the study shows that over the period from 1901 to 2007, it was possible to negate the damage to cables caused by fish. From 1901 to 1957, 28 such injuries were recorded. From 1959 to 2006 there were already 11 cases, and since 2007 they have not been observed at all.

Modern cables because of their design of sharks simply can not bite. In addition, in many areas cables are buried in the ground and do not “disturb” the marine inhabitants.

How Do they Repair Cables?

Repair of submarine cables is carried out with the help of specially equipped ships, which are less than 10 in the world. One of such ships is a ship Le Pierre de Fermat with a length of 100 meters and a crew of 80 people.

The most difficult part in repairing a cable is finding the damaged area. For this, a 9-ton Hector robot is used, equipped with cameras and claws. With it, the right part of the cable rises aboard for repair. Fixing often involves installing a new cable section instead of the damaged one.

The chief engineer of the crew, Willie Poulain (Willy Poulain), says that in recent years the repair process has not changed, and this is not expected in the near future. How to repair, you can watch in this video.

How is Cables Strengthen?

A typical fiber-optic cable for a depth of more than 2,000 meters consists of an internal optical core encased in steel with high tensile strength and a copper conductor. For insulation, polyethylene is used. The diameter of this cable is 17-21 millimeters.

  • At depths of less than 2,000 meters, environmental protection from steel and polypropylene is added. If necessary, several layers of such “armor” can be used. The tensile strength of the most “protected” cable reaches 70 tons.

Breakages also occur because the cable in the process of operation is twisted to values less than the recommended radius. Therefore, for the rupture of enough anchors and fishing equipment.

In most regions, failure of one cable will not significantly affect the quality of the connection – traffic is simply redistributed through other channels. But there are still such regions that are connected to the “big earth” by a single wire. One of them is the Northern Mariana Islands in the western part of the Pacific Ocean. When this cable went down due to the typhoon in 2015, 54 thousand people were temporarily left without internet and phone.

With all the shortcomings, there are no real alternatives to cables yet. Satellite communication cannot provide the necessary bandwidth. And alternative technologies, such as laser-radio and quantum Internet are still far from being realized “among the masses”.