Kronprinzenkoog is a municipality in the district of Dithmarschen, in Schleswig-Holstein, Germany. Between 1785 and 1787, the polder was laid out and then named in honour of Crown Prince Frederick of Denmark.
Wikipedia https://en.wikipedia.org/wiki/Kronprinzenkoog
Coordinates 53°58'15.229" N 8°57'39.426" E