Visiting the Maeslantkering storm barrier across the river Maas, one of the tributaries of the Rhine delta. It’s difficult to comprehend the size of the huge construction, whose purpose is similar to the Thames Barrier but also allows shipping to pass upstream to the port of Rotterdam. Each of the two gates is the same length as the height of the Eiffel Tower; when swung across the channel and filled and sunk with water, they can stop an incoming storm surge from the North Sea from overtopping the dykes in South Holland. This protection wasn’t available in 1953 with the result of more than 1700 deaths and many, many homes flooded. The Maeslantkering is tested annually but has only been required to be closed once so far for real protection, in November 2007. Rising sea levels and climate change will require it to be deployed more frequently in the near future.