ZUYDER ZEE, zoi'disr 25, or ZUIDER ZEE. A large arm of the North Sea. penetrating deeply into the northwestern part of the Netherlands (Map: Netherlands, D 2). It- consists of an oval inner portion 44 miles long and about 30 miles broad, separated by a strait about ten miles wide from the horn-shaped outer portion, which in turn is separated from the North Sea by the line of sandy islands consisting of Texel, Vlieland, Terschelling, and .Ameland. Northeast of Ameland the sea is connected by the shallow channel known as the Wadden with the estuary of the Ems. The total area of the sea, includ ing the Wadden. is 2027 square miles. The largest river flowing into it is the Yssel, an arm of the Rhine. The Zuyder Zee was originally an inland lake, the outer portion being dry land connecting the present peninsulas of North ITob land and Friesland, and having a continuous coast-line now indicated by the outer line of the Frisian Islands. The lake received the River Yssel, and had a narrow outlet between the present islands of Vlieland and Tersehelling. Several severe storms, the principal occurring in the thirteenth century, caused the North Sea to break through the line of dunes at several places and inundate the lowlands between it and the lake, converting the latter into an arm of the sea. This origin explains the remarkable shal
lowness of the Zuyder Zee, especially of the outer portion, where large sand and mud flats are exposed at low tide. The Mean depth of the inner portion is about 12 feet and the maximum 20, while over large areas the depth is three feet or less at low tide. The strait connecting the inner and outer portions, and the main channels leading into the open sea have, however, a depth of 30 to 40 feet. Since the Zuyder Zee is accord ingly unimportant for navigation, the main ship route to Amsterdam being through canals lead ing directly from the North Sea, and since the fisheries have also declined, it has been proposed to reclaim the inner sea by damming and drain ing it. A commission rendered favorable reports in 1894 and 1897: and in 1900 a bill was intro duced providing for the work, but it was with drawn in the following year. The work was estimated to require 32 years for completion and to cost about $36,000.000, which the Government expected to recover by the sale of the reclaimed land.