Artificial island

Despite a popular image of modernity, artificial islands actually have a long history in many parts of the world, dating back to the reclaimed islands of Ancient Egyptian civilization, the Stilt crannogs of prehistoric Wales, Scotland and Ireland, the ceremonial centers of Nan Madol in Micronesia and the still extant floating islands of Lake Titicaca.[3] The city of Tenochtitlan, the Aztec predecessor of Mexico City that was home to 500,000 people when the Spaniards arrived, stood on a small natural island in Lake Texcoco that was surrounded by countless artificial chinamitl islands.

Reef Island off North Malaita.

The people of Langa Langa Lagoon and Lau Lagoon in Malaita, Solomon Islands, built about 60 artificial islands on the reef including Funaafou, Sulufou, and Adaege.[4][5] The people of Lau Lagoon build islands on the reef as this provided protection against attack from the people who lived in the centre of Malaita.[6][7] These islands were formed literally one rock at a time. A family would take their canoe out to the reef which protects the lagoon and then dive for rocks, bring them to the surface and then return to the selected site and drop the rocks into the water. Living on the reef was also healthier as the mosquitoes, which infested the coastal swamps, were not found on the reef islands. The Lau people continue to live on the reef islands.[4]

Many artificial islands have been built in urban harbors to provide either a site deliberately isolated from the city or just spare real estate otherwise unobtainable in a crowded metropolis. An example of the first case is Dejima (or Deshima), created in the bay of Nagasaki in Japan's Edo period as a contained center for European merchants. During the isolationist era, Dutch people were generally banned from Nagasaki and Japanese from Dejima. Similarly, Ellis Island, in Upper New York Bay beside New York City, a former tiny islet greatly expanded by land reclamation, served as an isolated immigration center for the United States in the late 19th and early 20th century, preventing an escape to the city of those refused entry for disease or other perceived flaws, who might otherwise be tempted toward illegal immigration. One of the most well-known artificial islands is the Île Notre-Dame in Montreal, built for Expo 67.

The Venetian Islands in Miami Beach, Florida, in Biscayne Bay added valuable new real estate during the Florida land boom of the 1920s. When the bubble that the developers were riding burst, the bay was left scarred with the remnants of their failed project. A boom town development company was building a sea wall for an island that was to be called Isola di Lolando but could not stay in business after the 1926 Miami Hurricane and the Great Depression, dooming the island-building project. The concrete pilings from the project still stand as another development boom roared around them, 80 years later.

A large amount of sand is required to build these islands. Dredging can cause sand to stir up and deposit on reefs, disrupting marine life.[17] The increased amount of sand and fine particles of sediments creates more turbid conditions, which blocks the necessary UV rays from reaching coral reefs and creates coral turbidity (More organic material is taken in by coral) and increased bacterial activity (More harmful bacteria are introduced into coral).[18][19]

The implementation of artificial islands can decrease the subaqueous area in surrounding waters, leading to habitat degradation for many species.[19]

Under the United Nations Convention on the Law of the Sea treaty (UNCLOS), artificial islands are not considered harbor works (Article 11) and are under the jurisdiction of the nearest coastal state if within 200 nautical miles (370 km) (Article 56).[20] Artificial islands are not considered islands for purposes of having their own territorial waters or exclusive economic zones, and only the coastal state may authorize their construction (Article 60);[21] however, on the high seas beyond national jurisdiction, any "state" may construct artificial islands (Article 87).

The micronation known as the Principality of Sealand (often shorted to simply "Sealand") is entirely on a single artificial island.

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  A view of Kansai International Airport from space
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  Palm Jumeirah in Dubai
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  A closer view of the Palm Jumeirah
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  Northstar Island, an artificial island for oil drilling in the Beaufort Sea

Wikimedia Commons has media related to Artificial islands.

• Artificial Islands in The Law of the Sea