ZUIDER ZEE, or Zuyder Zee, a land-locked inlet on the coast of Holland, bounded N. by the chain of the Frisian Islands, and W., S., and E. by the provinces of North Holland, Utrecht, Gelderland, Overysel, and Friesland. It is about 85 m. long N. to S., and from 10 to 45 m. broad, with an area of 2027 sq. m., and contains the islands of Marken, Schokland, Urk, Wieringen, and Griend. In the early centuries of the Christian era the Zuider (i.e. Southern) Zee was a small inland lake situated in the southern part of the present gulf, and called Flevo by Tacitus, Pliny, and other early writers. It was separated from the sea by a belt of marsh and fen uniting Friesland and North Holland, the original coast-line being still indicated by the line of the Frisian Islands. Numerous streams, including the Vecht, Eem, and Ysel, discharged their waters into this lake and issued thence as the Vlie (Latin Flevus), which reached the North Sea by the Vliegat between the islands of Vlieland and Terschelling. In the Lex Frisonum the Vlie (Fli, or Flehi) is accepted as the boundary between the territory of the East and West Frisians. In time, however, and especially during the 12th century, high tides and north-west storms swept away the western banks of the Vlie and submerged great tracts of land. In 1170 the land between Stavoren, Texel, and Medemblik was washed away, and a century later the Zuider Zee was formed. The open waterway between Stavoren and Enkhuizen, however, as it now exists, dates from 1400. In the south and east the destruction was arrested by the high sandy shores of Gooi, Veluwe, Voorst, and Gasterland in the provinces of Utrecht, Gelderland, Overysel, and Friesland respectively.
The mean depth of the Zuider Zee is 11.48 ft.; depth in the southern basin of the former lake, 19 ft.; at Val van Urk (deep water to the west of the island of Urk), 14½ ft. If a line be drawn from the island of Urk to Marken, and thence westwards to Hoorn (North Holland) and N.N.E. to Lemmer (Friesland), these lines will connect parts of the Zuider Zee having a uniform depth of 8 ft. The other parts on the coast are only 3 ft. deep or less. This shallowness of its waters served to protect the Zuider Zee from the invasion of large ships of war. It also explains how many once flourishing commercial towns, such as Stavoren, Medemblik, Enkhuizen, Hoorn, Monnikendam, declined to the rank of provincial trading and fishing ports. The fisheries of the Zuider Zee are of considerable importance. Eighty per cent. of the bottom consists of sea clay and the more recent silt of the Ysel; 20 per cent. of sand, partly in the north about Urk and Enkhuizen, partly in the south along the high shores of Gooi, Veluwe, &c. The shallowness of the sea and the character of its bottom, promising fertile soil, occasioned various projects of drainage. The scheme recommended by the Zuider Zee Vereeniging (1886) formed the subject of a report in 1894 by a state commission. The principal feature in the scheme was the building of a dike from the island of Wieringen to the coast of Friesland. The area south of this would be divided into four polders, with reservation, however, of a lake, Yselmeer, in the centre, whence branches would run to Ysel and the Zwolsche Diep, to Amsterdam, and, by sluices near Wieringen, to the northern part of the sea. The four polders with their areas of fertile soil would be:—
|(1)||North-west||polder, area||53,599||acres; fertile soil,||46,189||acres.|
The Lake Yselmeer would have an area of 560 sq. m. The gain would be the addition to the kingdom of a new and fertile province of the area of North Brabant, a saving of expenses on dikes, diminution of inundations, improvement of communication between the south and the north of the kingdom, protection of isles of the sea, &c. The costs were calculated as follows: (1) enclosing dike, sluices, and regulation of Zwolsche Diep, £1,760,000; (2) reclamation of four polders, £5,200,000; (3) defensive works, £400,000; (4) indemnity to fishermen, £180,000; total, £7,540,000.
In 1901 the government introduced a bill in the States General, based on the recommendations of the commission, providing for enclosing the Zuider Zee by building a dike from the North Holland coast, through the Amsteldiep to Wieringen and from that island to the Friesland coast at Piaam; and further providing for the draining of two portions of the enclosed area, namely the N.W. and the S.W. polders shown in the table. The entire work was to be completed in 18 years at an estimated cost of £7,916,000. The bill failed to become law and in consequence of financial difficulties the project had not, up to 1910, advanced beyond the stage of consideration.
With the exception of Griend and Schokland, the islands of the Zuider Zee are inhabited by small fishing communities, who retain some archaic customs and a picturesque dress. Urk is already mentioned as an island in 966. The inhabitants of Schokland were compelled to leave the island by order of the state in 1859, it being considered insecure from inundation. The island of Griend (or Grind) once boasted a walled town, which was destroyed by flood at the end of the 13th century. But the island continued for some centuries to serve as a pasturage for cattle, giving its name to a well-known description of cheese. Like some of the other islands, sheep are still brought to graze upon it in summer, and a large number of birds' eggs are collected upon it in spring. Several of the islands were once the property of religious houses on the mainland.
The British Foreign Office report, Draining of the Zuiderzee (1901), gives full particulars of the Dutch government's scheme and a retrospect of all former proposals. See also De economische beteekens van de afsluiting en drooglegging der Zuiderzee vom Zuiderzee-Verein (2nd ed., 1901), and D. Bellet, “Le dessèchement du Zuiderzee,” Rev. Geog. (1902) and W. J. Tuyn, Oude Hollandsche Dorpen aan de Zuiderzee (Haarlem, 1900).