The Markermeer is a vast 700 sq km lake near Amsterdam that has become the site of a new Dutch archipelago. It is called Marker Wadden, and the 1,300 hectare site is comprised of seven artificial islands that ecological engineers, landscape architects and a dredging company have built since 2016. Using sand and mud taken from the lake floor, they have created a sprawling environment which is a haven for plants, birds and other wildlife. It is a wonderful example of how engineering can be used for ecological restoration.   The lake was once part of a long inlet of the North Sea that reached the outskirts of Amsterdam. In 1932, they built a dyke across its mouth creating a vast salt water lake that was cut off from the ocean. In 1975, a second dyke divided this lake into two parts, with Markermeer as the inner lake. The water gradually turned from salt water to fresh, but eventually the lack of circulation from river input killed the vegetation, and the lake became a “dead zone.” The work to restore the lake and create Marker Wadden began by dredging up mud and silt from the bottom to make barriers that would clean the water and direct its flow. Protected within these barriers, they began to create the islands. The project took six years to complete, and used 37 million tonnes of material that was dredged almost entirely from the lake floor.    The seven islands are enveloped by dunes and beaches. The natural plant life of the area has thrived in this pristine setting. As the landscape matured, more and more vegetation appeared, and this has attracted a wide range of avian species. At last count there were over 50 breeding bird species on the islands. In addition, many birds that breed elsewhere are stopping here as they migrate. About 60,000 of these migratory birds seek food and shelter at Marker Wadden every year. And it is not only birds that visit these man-made wonders. Last year over 50,000 tourists came to spend the day, and this paid for 70% of the cost of upkeep and site management.