Zuider Zee

(dər zē; Du zo̵ir)

former arm of the North Sea, which extended into the Netherlands: its S section was shut off from the North Sea by dikes

See Zuider Zee in American Heritage Dictionary 4

A former shallow inlet of the North Sea in northeast Netherlands. Originally a lake, it was joined with the North Sea by heavy flooding. A dike, completed in 1932, turned the southern section into the Ijsselmeer, which has largely been reclaimed for agriculture.
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