The Zuiderzee became IJsselmeer when in 1927 the construction of the Afsluitdijk was finished.
In 1932, at the Vlieter, the last hole in the dike was closed. This spot is marked by a little White Tower, monument the Vlieter.
By the construction of the Afsluitdijk the salt water of the Zuiderzee changed gradually in freshwater. The closure had implications for the intensive fishing on the former Zuiderzee.