Submarine cables

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Landing while laying a transatlantic cable at Rockaway Beach , New York, September 1924 with wooden barrels.
Work in the coastal area to connect a submarine cable, 1997

A submarine cable (sometimes also called underwater cable ) is a cable laid in a body of water for data transmission or for the transmission of electrical energy . Submarine cables for power transmission are no longer suitable for the transmission of conventional three-phase alternating current from a length of around 70 km , in which case the more complex high-voltage direct current transmission (HVDC) must be used. They are mostly laid by special ships, so-called cable layers .

Gerhard Pauly ( Deutsche Telekom ) on intercontinental cable (1996)

Due to the technically complex maintenance, submarine cables have to be extremely robust. Monopolar submarine cables for high-voltage direct current transmission must be marked on nautical charts , as their magnetic field can significantly disrupt compass systems on ships. In 2014, 95 percent of Internet traffic between regions of the world was carried by submarine cables. Between 2012 and 2014 a large number of new undersea cables were laid and the number rose from 150 to 285 cables worldwide.

Telecommunication cables in the deep sea

Structure of a submarine cable with optical fibers
(1 - polyethylene, 2 - Mylar tape, 3 - steel wires, 4 - aluminum water protection, 5 - polycarbonate, 6 - copper or aluminum pipe, 7 - Vaseline, 8 - optical fiber)
Section through a telecommunications cable with copper conductors

Deep-sea cables enable data communication over great distances and can transport amounts of data that are larger than those of the most powerful communication satellites . Another advantage over satellite connections is the significantly shorter signal transit time . However, they share a major disadvantage with satellites: Just like satellites, deep-sea cables can only be modified, maintained, expanded or otherwise edited afterwards with great effort.

Because of the high volume of data, deep-sea cables are used particularly frequently in the Atlantic between North America and Europe. There are only a few countries that do not yet have a connection to a high-performance communications cable.

At the beginning, analog electrical signals were still transmitted. There are now strands of fiber optic cables on the seabed . A fiber optic cable contains several pairs of fibers; the TAT-14 laid in the North Atlantic, for example, contains four. Using so-called “ multiplexing ”, many data streams can flow at once via a fiber pair . The latest fiber pairs can transmit a terabit of data per second. The fiber optic cables lie in a copper tube, which is filled with water-repellent composite material. Around this copper pipe is an aluminum tube to protect it from the salt water, followed by steel cables and, depending on the strength of the protection, several layers of plastic . The copper pipe also serves as an electrical conductor to supply power to the optical amplifiers looped into the cable, which are required at intervals (with modern cables 50–80 km) . The seawater serves as the return line for operating the amplifier. The operating voltage reaches the order of 10 kV. Stronger armored cables are used off the coasts because of the rising seabed and the associated risk of damage from ship anchors or fishing trawlers . However, these precautions do not always help either. On February 28, 2012, a ship waiting on a berth in the port of Mombasa cut a submarine cable with its anchor and thus paralyzed a substantial part of the Internet connection in East Africa .

Laying of submarine cables

Laying submarine cables (animation)

In shallow water, the pipes are buried in the seabed using special vehicles. With a so-called laying plow , also known as a sea plow , water is sprayed from the vehicle's water tank under high pressure of 1600 bar into the sand on sandy soil, so that quicksand is created and the cable can sink in. The sand then solidifies again and covers the cable. At the beach, the cable is fed into a shaft and directed to the landing site. The laying work with the sea plow can only be carried out at low tide and requires optimal soil conditions.

Nessie II, a laying cutter for max. 14 m water depth

Another method for laying near the coast is to mill submarine cables with a submarine cable milling machine. This type of laying can also be used with changing soil conditions up to a laying depth of 10 m, even with changing tides. The machine opens the seabed with a milling chain. The laying shaft holds the milling trench behind the milling chain. The submarine cable runs through the installation shaft and leaves it at the lowest point. The excavated material is ejected behind the laying shaft by the milling chain and almost completely backfills the trench. The rest of the backfilling is done by the tides.


Telegraph cable

Drawings of the presumed relief of the sea floor in the Central Atlantic from 1858 ( Harper's Weekly )
Map of the cable route from 1858
Contemporary illustration of the cable break on the Great Eastern ( Illustrated London News )

As early as 1811, the German Samuel Thomas von Soemmerring was sending electrical signals through a rubber-insulated wire that had been laid through the Isar near Munich .

However, these early attempts mainly suffered from suitable insulation. Since the invention of the electric telegraph, several methods have been tried out for the idea of ​​laying underwater cables . But it wasn't until Werner Siemens invented the gutta-percha press in 1847 that well-insulated cables were possible for underwater installation .

On August 28, 1850, the first submarine cable was laid between Dover and Cap Gris-Nez near Calais , but it was interrupted by a fishing boat with its nets the next day after the first telegram was transmitted . A year later, an armored submarine cable was laid between Great Britain and France. This proved itself and triggered the laying of further submarine cables - with not always a long service life.

Further attempts, such as laying a cable in the Mediterranean between Algeria and Sardinia , initially failed due to inadequate equipment. For example, there was no suitable cable brake that could be used to control the unwinding of the cable from the cable drum even in great water depths. One of these only became available with Werner Siemens' brake dynamometer .

Transatlantic cable

Since it took more than a week to send a message from America to Great Britain in the mid-19th century, Cyrus W. Field came up with the idea of ​​laying a cable on the ocean floor of the Atlantic.

In 1856 the "Atlantic Telegraph Co." was founded in order to raise the necessary funds through the sale of shares. A cable over 4500 kilometers long was to be laid from Ireland to Newfoundland . The ships used, the Agamemnon and Niagara , began in Ireland on August 3, 1857, but had to give up after several recoverable cable losses and breaks after some time after the final loss of the cable.

The laying of the 2200 English mile long submarine cable between Europe (London) and the USA began in the spring of 1857. After exercises in the Bay of Biscay in the spring of 1858 and a hapless attempt in June 1858, the company finally succeeded in the third attempt, which began on July 17, after some difficulties, and on August 5 the connection was established. On August 16, 1858, this first deep-sea cable between South West Ireland and Newfoundland was put into operation with the exchange of congratulatory telegrams between Queen Victoria and the American President James Buchanan . However, the initial attraction turned into a major bankruptcy, as it took 16 hours to transmit the British Queen's greeting message to the American President, although it was only 103 words. In September 1858 the cable failed; The gutta-percha coating was probably damaged during laying, which meant that the cable was no longer adequately protected from corrosion by the seawater. The problem was that back then the topography and nature of the seabed were hardly known.

In 1864 a 5100 kilometer long submarine cable with improved protective sheathing was prepared and the " Great Eastern " was procured as a laying ship, at that time the largest liner in the world. On July 31, 1865, the cable tore while being laid. Only in 1866 could the first cable be laid with the second attempt, which would secure the telegraph connection between America and Europe in the long term.

More submarine cables to Africa

A few years later, the British finally succeeded not only in reaching the USA by submarine cable, but also the African continent via Freetown in Sierra Leone. Another submarine cable ran via Freetown to Cape Town.

Egypt became an important relay station for submarine cable telegraphy. In 1868 a submarine cable was laid from the island of Malta to Alexandria in Egypt. From 1870 this section indirectly connected London with Bombay.

The high ohmic resistance of the lines of these long cables weaken the signal very much, so the incoming signal had to be evaluated using a mirror galvanometer . The large transverse capacitance of the conductors and their longitudinal inductance cause signals to rise and fall slowly, so that only sufficiently slow telegraphy was possible and no sound transmission of voice ( telephony ).

Legal and political aspects

In 1884 the International Treaty for the Protection of Undersea Telegraph Cables was signed.

In 1911, the telegraph pioneer Adolf Slaby explained to the Colonial Technical Commission of the Colonial Economic Committee the importance of the submarine cables for secret communication as follows:

“The most important and most interesting does not immediately reach the public. The importance that the Navy today attaches to spark telegraphy has prompted it to incessantly incite inventors to make ever more progress. But the results and the means by which this has been achieved are no longer published today, they are kept secret. One should consider that in the Navy, wireless telegrams are not only transmitted from a squadron unit, but are exchanged with fleets 1,000 and more kilometers away, that these telegrams seek a route which is simply prescribed for them by the telegraph operator and which do not interfere with one another . "

Telephone cables

From 1950 submarine cables with spliced-in amplifiers for the transmission of telephone signals became possible. The amplifiers were supplied with high voltage via the inner conductor of the cable, the return conductor was the sea. In 1956 the first transatlantic telephone cable was laid.

Fiber optic cable

Repair of a submarine cable (animation)

By the early 1980s, optical communications had matured to the point that in 1980 the British Postal Administration tried to lay the first fiber optic cables in Loch Fyne , Scotland . In 1984 the first fiber optic connection from the island to the Isle of Wight went into operation, in 1986 through the English Channel. In 1988, TAT -8, the first transatlantic fiber optic cable, went into operation. By the mid-1990s, copper cables were practically completely displaced , also due to the expansion of capacity required by the development of the Internet .

Intelligence surveillance

As carriers of large amounts of data in overseas communications, submarine cables have been of interest to intelligence services since their development. With Operation Ivy Bells, the USA siphoned off a Soviet submarine cable from the Pacific fleet from 1971 to 1981 at great expense . It is known that the British GCHQ at the Cypriot Yeroskipos Submarine Cable Station monitors the global communication traffic via SEA-ME-WE 3 and possibly other submarine cables. In 2015, Trevor Paglen photographed a surveillance cable allegedly belonging to the NSA / GCHQ over a submarine cable in the Atlantic for his photo project Columbus III. Russian ships suitable for espionage and sabotage include the Jantar and Loscharik .

Power cable

In 1954, the first direct current power cable was laid between Gotland and mainland Sweden, followed by direct current submarine cables between Denmark and Sweden, Italy and Sardinia, the two islands of New Zealand and Great Britain and France in the 1960s.

Selected submarine cable systems

Cable laying machine on board the Oceanic Viking

Communication cable

Submarine cables laid worldwide (as of 2007)
Telecommunications submarine cables laid worldwide (as of 2015)
  • AC-1 (Europe ↔ North America)
  • ALBA-1 (Cuba ↔ Venezuela)
  • Apollo (Europe ↔ North America)
  • CANTAT (Canada ↔ Scotland)
  • COMPAC (Canada ↔ Hawaii ↔ New Zealand-Australia)
  • EASSy (East Africa ↔ Asia, Europe), in operation since July 30, 2010
  • HW (California ↔ Hawaii)
  • ICECAN (Iceland ↔ Greenland ↔ Canada)
  • SAFEC (Taiwan ↔ Japan)
  • SAT-3 / WASC / SAFE (South Africa, Namibia, Angola, Democratic Republic of the Congo, Republic of the Congo, Cameroon, Nigeria, Togo, Ghana, Ivory Coast, Cape Verde, the Canary Islands ↔ Portugal) completed since 1999 and 2000 respectively
  • SCOTICE (Scotland ↔ Iceland)
  • SEA-ME-WE (Southeast Asia ↔ Middle East ↔ Western Europe)
  • TAT (Great Britain ↔ North America)
  • TPC (Hawaii ↔ Japan)
  • Trans-Pacific-Express (TPE) (USA ↔ China)
  • Unity (America ↔ Asia), operational since April 1st, 2010
  • WACS (South Africa ↔ West Africa ↔ Portugal ↔ London), in operation since May 11, 2012
  • Marea (USA ↔ Spain)

Three-phase cable

DC power cable

see high-voltage direct current transmission (HVDC)

Planned submarine cables

  • The Internet company Google is planning to lay a submarine cable between Japan and the USA, the costs should be 300 million US dollars.
  • The Hansa Power Bridge is planned between Germany and Sweden .
  • With the "2Africa" ​​project, Facebook plans to provide 23 countries in Africa with faster internet. This is to be accomplished through 37,000 km of underwater fiber optic cable, at a cost of one billion dollars

Submarine cables in the literature

  • Stefan Zweig : Great moments of mankind . Anniversary edition. Fischer, Frankfurt am Main 2002. (Under the heading “The first word about the ocean”, Stefan Zweig describes the laying of the first transatlantic cable as a great moment for mankind)
  • John Griesemer : Intoxication . Piper Verlag, Munich 2005, ISBN 3-596-51000-7 . (a novel about the first submarine cable laying between Europe and America in the 19th century)
  • Hans-Jürgen Teuteberg, C. Neutsch (Ed.): From the wing telegraph to the Internet. History of Modern Telecommunications. Steiner, Stuttgart 1998.
  • John Steele Gordon: A Thread Across the Ocean: The Heroic Story of the Transatlantic Cable . Harper Perennial, 2003, ISBN 0-06-052446-4 .
  • William Thompson: The Cable: The Wire that Changed the World. Tempus, 2007, ISBN 978-0-7524-3903-7 .
  • Chester G. Hearn: Circuits in the Sea. The Men, the Ships, and the Atlantic Cable . Praeger, 2004, ISBN 0-275-98231-9 . (English)
  • Neal Stephenson : Mother Earth Mother Board. In: Wired . December 1996. (The laying of the submarine cable Fiber-Optic Link Around the Globe with its technical, economic and historical aspects was explored by the writer Neal Stephenson on a trip around the world in 1995/96 on behalf of Wired)


Web links

Commons : Submarine cables  - collection of images, videos and audio files

Individual evidence

  1. 1924 New York - Azores Cable. History of the Atlantic Cable & Undersea Communications,
  2. Interactive map plots growth of the submarine cable network since 1989 . In: Mail Online . ( [accessed January 6, 2017]).
  3. ^ Katja Riedel: When Queen Victoria called President Buchanan. On: Focus online.
  4. ^ Otto Lueger : Lexicon of the entire technology and its auxiliary sciences . 2nd Edition. Deutsche Verlagsanstalt, Stuttgart and Leipzig 1920 ( [accessed on May 29, 2019] lexicon entry "Seekabel").
  5. Unofficial part - newspaper news - London In: Osthavelländisches Kreisblatt , April 8, 1857, p. 2.
  6. International Treaty for the Protection of Undersea Telegraph Cables (1887). Wikisource
  7. Law for the Execution of the International Treaty for the Protection of Undersea Telegraph Cables (German Reich, 1887). Wikisource
  8. ^ Rudolf Goldschmidt, Adolf Slaby: wireless telegraphy. In: Negotiations of the Colonial-Technical Commission of the Colonial-Economic Committee. Issue 1, 1911, p. 30.
  9. Trevor Paglen photographs the undersea cables that are being tapped by the NSA. In: VICE. Retrieved January 6, 2017 .
  10. Analysis: Can Russian submarines cut the West's cables?
  11. ^ Submarine Cable Map . In: . ( [accessed September 25, 2017]).
  12. SAT-3 / WASC / SAFE. ( Memento of February 3, 2013 on the Internet Archive ) Official website
  13. ( Memento of the original from April 14, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  14. ( Memento of the original from April 13, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  15. Peter-Michael Ziegler: New information highway between China and the USA. In: Heise online . December 19, 2006, accessed on January 29, 2018 (German).
  16. ^ Unity Cable System Completed, Boosts Trans-Pacific Connectivity . Google Press Center, April 1, 2010; Retrieved February 21, 2011.
  17. WACS undersea cable update ., May 11, 2012; accessed on July 30, 2016.
  18. ^ Celebrating the completion of the most advanced subsea cable across the Atlantic ., September 21, 2017; accessed on September 23, 2017.
  19. ^ The Longest AC Subsea Cable in the World , Manx Electricity Authority , Retrieved October 22, 2008.
  20. ↑ Power cable through the middle of the Achensee from October 25, 2013.
  21. ABB Hannover Messe 2013: ABB shows 420 kV three-wire submarine cable - world record cable - economy - Nordic Market. In: Retrieved January 2, 2017 .
  22. Company Nexans on the cable project, accessed on November 12, 2019
  23. Gülnazi Yüce: Submarine Cable Projects (2-03) (PDF) presented at First South East European Regional CIGRÉ Conference (SEERC), Portoroz, Slovenis, 7.-8. June 2016, accessed April 8, 2018. (English)
  24. Google wants to swallow apartment surveillance company Dropcam from June 21, 2014.
  25. Microsoft and Facebook build new transatlantic cable. In: May 26, 2016. Retrieved May 26, 2016 .
  26. Facebook to build $ 1 billion undersea Internet cable for faster Internet in Africa