Constructed from 1991 to 1997, the Maeslant Barrier (Maeslantkering in Dutch) is a storm surge barrier on the Netherlands’ Nieuwe Waterweg ship canal. Operated entirely automatically, the structure responds to predicted flooding and so protects the residents of the province of South Holland. The Maeslantkering closes if the water level is predicted to rise to more than 3m above NAP (Normaal Amsterdams Peil – a reference measurement of the city’s water level) near Rotterdam. The huge barrier doors are in fact floating pontoons that can be filled with water. The additional weight makes them sink, creating the massive barrier. It is one of the largest moving structures on earth.
“This Maeslant Barrier is really here to safeguard us for the future.” – Henk Ovink, Dutch envoy to the UN and flood expert, speaking to CBS News