That all Dutch children must learn to swim by the age of six is a national mandate that probably makes sense. The Netherlands, of course, is a country of water – ocean, inland seas, rivers, and canals. A legacy of all those iconic windmills, vast regions of the Netherlands have been reclaimed from inland water bodies through massive water-pumping projects initiated in the 15th century and continuing ever since. Today, a quarter of the country's land lies below sea level, with more than 20% of the Dutch population residing in these areas. Of the remaining land area, most sits at only a few feet above sea level. So the likelihood of encountering water as a swimmer, even at a young age, seems great. What is perhaps most remarkable about this requirement, however, and most revealing about the Dutch national character, is not that all children must demonstrate proficiency in the water at a young age but rather that they must do so fully clothed. The Dutch are not preparing for a day at the beach; the Dutch are preparing for an emergency.

They have good reason to do so. At its lowest points, the Netherlands sits at 23 feet below sea level, exceeding the lowest elevations in New Orleans, for example, by about 16 feet. Such a pronounced change in elevation contributes not only to the depth of flood waters when levee systems fail but also to the rate at which flood waters rise. In past flooding events, the most catastrophic in February 1953, flood waters surged into low-lying areas without warning, yielding in a matter of hours a death toll equivalent to that of Hurricane Katrina. In the aftermath of the 1953 event, the Dutch undertook the construction of a massive flood-management system that would require almost a half-century to complete. Consisting today of more than 8,000 miles of levees, dikes, and sea barriers, the water-management system now protecting the Netherlands from rising seas is regarded by the U.S. Army Corps of Engineers as one of the seven wonders of the engineering world. But it will not safeguard the Dutch from climate change.