NAP (Normaal Amsterdams Peil)

NAP is the Dutch national height reference, short for Normaal Amsterdams Peil, which the Netherlands uses as its zero level for measuring heights. Ground levels, dykes, and water levels are given in metres above or below NAP, where 0 m NAP is approximately mean sea level at Amsterdam. Because so much of the country lies below this level, NAP is the standard way to describe how high or low water stands in the Netherlands.