After 1 February 1953, the dykes of Zeeland were broken in sixty-seven places, and they had to be closed one by one through a year of cold weather and short supplies. The breach near Ouwerkerk on Schouwen-Duiveland was the last and the worst — it kept widening with every tide, and ordinary materials would not hold. The Dutch found a solution by reusing four Phoenix caissons originally built by the Allies for the Mulberry harbour on D-Day, vast hollow concrete boxes that could be towed into place, sunk, and locked down with stone and clay. They sealed the gap at Ouwerkerk in November 1953. The same caissons are still there. They are the museum.

It took forty years for the survivors to be ready to build a museum. After the 1993 commemoration of the flood's fortieth anniversary, a working group formed around a Schouwen-Duiveland woman named Ria Geluk, who had lived through the flood as a child. By 1997 the group had momentum; volunteers led by Evert Joosse, an architect from Kloetinge, fitted out the first caisson; a trial opening followed in autumn 2000. On 2 April 2001, the Minister of Transport Monique de Vries cut the ribbon on a museum the survivors had built themselves. In July 2008 the expansion began. By April 2009 all four caissons were open and connected by underground corridors, and Prime Minister Jan Peter Balkenende re-opened the enlarged museum. In 2016 the Dutch government formally designated it the National Knowledge and Memorial Centre for the Flood of 1953.

Each caisson holds a chapter. The first is Facts. It tells what happened on the night and in the first days after — the dyke holes plugged with sandbags, the boats that converged from every nearby harbour to lift survivors off chimneys and roofs, the Polygoon newsreel footage that shocked the country into understanding what its southwest had endured. The second caisson is Emotions. This is where the multimedia monument 1835+1 lives, where the names of every known victim are inscribed in niches along the corridor, where photographs of survivors look back at you and where the relief that poured in from around the world — the postcards, the foreign helicopters, the pea soup sold door to door by Dutch soldiers — is remembered alongside the loss. The third caisson is Reconstruction: a replica of one of the prefabricated houses that Scandinavia donated by the thousand, the equipment used to rebuild the dykes, and the slow story of how the devastated polders came back. The fourth caisson is Future, with touchscreens and a reality-based game that lets visitors play with safety scenarios for the Rhine–Meuse–Scheldt delta. Rijkswaterstaat donated the equipment.

The official Dutch death toll was 1,836, but a museum is not a spreadsheet, and the working group understood that. Behind the names on the wall stand specific stories: a twenty-year-old man from Oude-Tonge named Jos de Boet who lost forty-two family members in a single night; a baby born and lost before she was named; entire neighbourhoods on Schouwen-Duiveland and Goeree-Overflakkee where there was no one left in the morning to tell who had been there before. The museum's task is to hold those particulars without flattening them into a number. The 2011 Siletto Award, which recognises museums for their work with volunteers, went to the Watersnoodmuseum partly because so many of the people telling the stories had lived them. That changes what a museum can do.

Walk out of the museum and you stand on the very dyke whose breach the caissons closed. The Oosterschelde stretches out to your west, framed by the Oosterscheldekering somewhere on the horizon. Birds work the mudflats. Inside, the building is dim and cool and very quiet. Outside, the wind is doing what wind always does on a Dutch dyke — testing the work. The museum is a promise the survivors made on behalf of the dead, and the promise is being kept by the people who come in and read the names. Ouwerkerk is a small village. The thing it has built here is not small at all.