Markermeer is a big shallow lake in the middle of the Netherlands, walled off from the sea decades ago, and for years the fine silt stirring through it clouded the water and left little for anything to live on. So Natuurmonumenten, the Dutch conservation society, tried something that sounds like a tall tale: build new land out of the very stuff causing the trouble. Dredgers lifted sand, clay and silt off the lake bed and laid it up into islands, shallow at the edges, with reed marsh and open sand and channels running through. First island was opened on 24 September 2016. Four more followed by 2021, about eight hundred hectares all up, better than one per cent of the whole lake.

What grew there has surprised everyone, including the people who built it. More than two hundred species of bird have been recorded on the islands, and in the early years roughly eight in every hundred avocets nesting anywhere in the Netherlands nested here. Young fish fill the shallows. Elsa Pater, the ranger at Marker Wadden, puts her finger on why it works: bare open ground, she says, is getting scarce in her country, and there are creatures that need exactly that and nothing else. Boskalis has just finished laying wide beaches around the outer edges to take the force of the waves, which should carry the islands another decade. You can catch a boat out from Lelystad, walk the paths, climb the lookout, and stay the night.

Our short take: figures from Natuurmonumenten (15 February 2026) and NOS Nieuws, reporting with Omroep Flevoland (6 March 2026). Photograph: to be chosen, three options on the photo page.