Nope, it's not. It's always (sortof) closed. It's named that way because it closed of a large part of sea, and turned it into a lake. The Oosterscheldekering do

Nope, it's not. It's always (sortof) closed. It's named that way because it closed of a large part of sea, and turned it into a lake. The Oosterscheldekering does open and close. https://en.wikipedia.org/wiki/Afsluitdijk https://en.wikipedia.org/wiki/Afsluitdijk https://en.wikipedia.org/wiki/Oosterscheldekering https://en.wikipedia.org/wiki/Oosterscheldekering