This fascinating display was closed for repairs at the time of research, but shows the ins and outs of Normaal Amsterdams Peil (NAP; Normal Amsterdam Level). Established in the 17th century as the average high-water mark of the Zuiderzee, it still forms the zero reference for elevation countrywide and is now used throughout the EU as the European Vertical Reference System (EVRS).
Water columns here represent different sea levels, as well as disastrous flood levels in 1953 (4.55m above NAP). Information sheets and a touchscreen explain the details.