Wadden Sea

The largest unbroken system of intertidal sand and mud flats in the world, a band of channels, tidal flats, salt marshes and barrier islands running along the North Sea coast of the Netherlands, Germany and Denmark. Twice-daily tides expose and reflood roughly half the ecosystem's area, and the vast biomass of worms, shellfish and other invertebrates living in the exposed flats makes the Wadden Sea one of the most important staging and wintering grounds on the East Atlantic Flyway, hosting more than ten million migratory shorebirds and waterbirds in an average year. The Netherlands and Germany jointly inscribed the site as a UNESCO World Heritage property in 2009, extended to the Hamburg Wadden Sea in 2011 and to the Danish Wadden Sea in 2014, bringing the full trilateral site to roughly 11,500 square kilometers.