Our programming today was fully dedicated to visiting the engineering marvel that is the Dutch Delta Works. Constructed between 1954 and 1997, the Delta Works are a system of dams, dikes, locks, and storm surge barriers located in the provinces of South Holland and Zeeland, protecting the land around the Rhine–Meuse–Scheldt delta from the North Sea. Dikes and dams existed before 1954, but the devastating floods of 1953, which killed 1,836 people, sparked the Delta Act, launching the Delta Project with the goal of closing all tidal inlets in the delta. The plan kept the New Waterway and Western Scheldt open, as they were essential shipping and passenger routes to Rotterdam and Antwerp respectively.

We specifically visited the Eastern Scheldt Storm Surge Barrier, which is 3,000 meters long and spans three tidal channels: the Hammen, Schaar van Roggenplaat, and Roompot. The barrier was constructed between 1979 and 1986. A storm surge barrier was chosen over a dam because it would allow two-thirds of the natural tidal range to be preserved, protecting the local ecosystem. The combined structure consists of sixty-six prefabricated concrete piers and sixty-three sliding steel gates. The gates remain open under normal conditions, but when dangerously high water levels are forecast, typically once every one to two years, they are closed to protect the islands of the region.

The construction of the barrier was one of the most complex and remarkable infrastructure projects of the 20th century, earning the Delta Works recognition as one of the Seven Wonders of the Modern World. Nothing like it had ever been attempted before, meaning all techniques, machinery, and plans had to be designed from scratch.

The completed barrier was built using multiple prefabricated components. The most involved of these were the piers — 18,000-ton concrete supports constructed in a specially built dry dock. The dry dock would be flooded so that a purpose-built vessel called the Ostrea (oyster) could lift the piers, transport them to the project site, and install them with the assistance of another specially fabricated pontoon, the Macoma (mollusk). The Ostrea could only lift 10,000 tons, but by exploiting the natural buoyancy of the piers before they were filled with sand, their effective weight was reduced to 9,000 tons.

Another critical component was the foundation mattresses, which were used to reduce erosion around the piers while creating a level seabed for installation. Each mattress measured 200 by 42 meters and was constructed from a combination of synthetic fabrics, steel, gravel, and sand. Laying these mattresses required seven specially manufactured vessels:

• The Johan V. – a geotechnical surveying pontoon
• The Cardium (cockle) – a dredging vessel used to lay the mattresses
• The Jan Heijmans – a modified asphalt barge that infilled spaces between the mattresses as well as helped to align the mattresses
• The Donax II – a floating cylinder used to transport the mattresses
• The Donax I – which towed and positioned the Donax II
• The Sepia – a modified pontoon for laying other mattresses that overlaid joints in the main mattresses
• The Macoma – which anchored the everting in place while it was being laid

This illustrates just how complex the installation of a single component was. Five additional parts — the steel gates, sill beam, upper beam, road bridge, capping unit, and operating hydraulics — still had to be installed to complete the full structure.

The Delta Works are designed with an operational lifespan of 200 years. But with climate change accelerating faster than anticipated, the Netherlands is already planning its next generation of innovations in water management.