An artificial island or man-made island is an island or archipelago that has been constructed by people rather than formed by natural means. They are created by expanding existing islets, construction on existing reefs, or amalgamating several natural islets into a bigger island.
Early artificial islands included floating structures in still waters, or wooden or megalithic structures erected in shallow waters (e.g., crannógs and Nan Madol discussed below). In modern times artificial islands are usually formed by land reclamation, but some are formed by the incidental isolation of an existing piece of land during canal construction (e.g. Donauinsel and Dithmarschen), or flooding of valleys resulting in the tops of former knolls getting isolated by water (e.g. Barro Colorado Island).
Some recent developments have been made more in the manner of oil platforms (e.g., Sealand and Republic of Rose Island).
Artificial islands may vary in size from small islets reclaimed solely to support a single pillar of a building or structure, to those that support entire communities and cities.
Despite a popular image of modernity, artificial islands actually have a long history in many parts of the world, dating back to the crannogs of prehistoric Scotland and Ireland, the ceremonial centers of Nan Madol in Micronesia and the still extant floating islands of Lake Titicaca. 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.
Largest artificial islands according to their size:
# Name Size (km²) Country Utilisation
1 Flevopolder 970 Netherlands towns, agriculture
2 Yas Island 25 Abu Dhabi Yas Marina Circuit
3 Palm Jebel Ali 8 Dubai
4 Chūbu Centrair International Airport 6.8 Japan Airport
5 Palm Jumeirah 5.65 Dubai housing
6 Kansai International Airport 4 Japan Airport