- 374.5 square mile(s)
- Netherlands (Flevoland)
By far and away the world’s largest artificial island is the 374.5-square-mile Flevopolder in Flevoland, Netherlands. Formed as part of the massive 1919–1986 Zuiderzee system of dames, dikes, land-reclamation and drainage projects, Flevopolder’s island status is granted by being completely surrounded by the bordering lakes of Gooimeer, Ketelmeer and Veluwemeer. Engineering works first required the damming off of parts of the Zuiderzee sea inlet, using the Afsluitdijk dam (1932) to create the new fresh water IJssel Lake. After World War II, land-reclamation works created the eastern Felvopolder (1957) and then the southern Flevopolder (1968). On 1 January 1986, Flevoland officially became the youngest and 12th province of the Netherlands.
Today, the area includes the cities Lelystad and Almere, and has a population of over 400,000.