People have been building islands by hand for well over a thousand years
Artificial islands sound like a Gulf megaproject, but Bahrain's Al-Sayah Island was raised around a spring at least 1,200 years ago. In Solomon Islands lagoons, families still live on reef islands their ancestors built by diving for rocks one at a time and dropping them from canoes.
Archaeologists trace island-making back to the Neolithic. Early versions ranged from floating platforms in calm water to wooden or stone structures set in shallows, such as the crannogs of prehistoric Scotland, Wales and Ireland and the ceremonial complex of Nan Madol in Micronesia. The floating islands of Lake Titicaca are still in use. Aztec Tenochtitlan, home to about 500,000 people when the Spaniards arrived, grew from a small natural island in Lake Texcoco ringed by countless man-made chinamitl plots.
On Malaita, the Lau and Langa Langa lagoon peoples built some 60 islands on the reef, including Sulufou. Living offshore protected them from raids by inland groups and kept them away from the mosquitoes of coastal swamps. Harbour islands served other ends. Japan's Edo-period rulers created Dejima in Nagasaki Bay to contain European traders, barring Dutch merchants from the city and Japanese from the island, and Ellis Island, a tiny islet enlarged by reclamation, kept rejected immigrants from slipping into New York.
Speculation left its own scars. Miami Beach's Venetian Islands added land during the 1920s Florida boom, but a planned island called Isola di Lolando collapsed after the 1926 hurricane and the Great Depression; its concrete pilings still stand eight decades later. Montreal's Île Notre-Dame, by contrast, was built for Expo 67. Bahrain's US$6 billion Durrat Al Bahrain strings 15 islands over about 5 square kilometres, including fish- and crescent-shaped ones.
Most modern islands come from land reclamation, though flooding can cut off hilltops too, as with Barro Colorado Island; René-Levasseur Island formed when two reservoirs filled. Builders can now work in water up to 75 metres deep, with wave size and structural strength setting the limit. The giant is the Netherlands' Flevopolder, completed in 1969 as part of the Zuiderzee Works, whose 970 square kilometres make it by far the largest reclaimed island. Since 2016 the Dutch have also built Marker Wadden, an entire archipelago for birds and wildlife. Oddly, no clear legal definition of an artificial island exists.
Source: Artificial island
