This edifice was built between 1955 and 1971. To build it, an artificial island was created in the middle of the estuary. The final phase of the project was completed with the aid of a cable car. Five km long, the dam incorporates 17 sluices in the middle which help to maintain the balance between fresh and salt water. As these are closed during normal operation, the water is kept in the Nieuwe Waterweg (New Waterway). A navigation lock has been created to the south, near the small harbour.