Schokland was a peninsula that by the 15th century had become an island. Occupied and then abandoned as the sea encroached, it had to be evacuated in 1859. But following the draining of the Zuider Zee, it has, since the 1940s, formed part of the land reclaimed from the sea. Schokland has vestiges of human habitation going back to prehistoric times. It symbolizes the heroic, age-old struggle of the people of the Netherlands against the encroachment of the waters.

Źródło: World Heritage Convention
http://whc.unesco.org/en/list/739