The New Student's Reference Work/Zuyder Zee

Zuyder Zee (zī'děr zē), a bay on the coast of, separated from the  or German Ocean by the four islands of Texel, Vlieland, Terschelling and Ameland. It is from 75 to 80 miles in length, its greatest breadth being 35 or 40 miles. In the time of the Romans the Zuyder Zee was a marshy lake communicating with the North Sea by a small river, but in the latter part of the 13th century two heavy inundations took place which broke down the dikes and submerged the whole territory, except the four islands named, making it an arm of the North Sea.