The Zuiderzee [ zɔɪdərze ː ] (also (obsolete) Zuider Zee Zuider Zee; Frisian Sudersee; Dutch [ zœydərze ː ] ) was a flat, only 4 m to 5 m deep bay of the North Sea in the northwest of present-day Netherlands. She passed about 100 km inland, was up to 50 km wide, covering 5000 km ². The name means " southern sea" in contrast to the North Sea ( in Dutch and Low German means zee " sea, the sea " and sea " the sea "). Both names are Friesian origin, are located north and south of their settlement area for the two seas. By damming the present IJsselmeer and some other inland lakes ( IJ, Lake Veluwe, Gooi-, sea marker, Drontermeer, Eemmeer and Ketelmeer ) thereof are formed.


Already the Romans knew a boggy, large-scale water landscape in this area, even if the actual lake, called Lacus Flevo was probably much smaller than the later Zuiderzee. Were these lakes landscape was probably since the seventh century BC. When storm surges, the water penetrated even then far into the flat and low-lying country from to gradually remove the marsh located behind the dunes at reflux. On the other side of the lake system has been brought on by tributaries of the river IJssel (right Ästuararm of Lek, on the German side, Issel on the right Lower Rhine ) as well as other streams and rivers, so that a large freshwater stream formed the north with time. The Flevosee was therefore with time called considerably larger and therefore soon Almere ( Aalsee ). (Today Almere is the name of a city in the province of Flevoland. )

With the Julianenflut in 1164, the All Saints' Day of 1170 and finally by the floods of 1219 (First Marcellus ) and in 1228 the salt water burst into the area a - the sand dike naturally formed was broken, from the inland waters was a bay in the north of the Netherlands. With the removal of the bottom floor of the new sea arose beside the Zuiderzee and the Waddenzee ( Wadden Sea ) on the south side of the present-day West Frisian Islands. After the annexation of the Kingdom of Holland by Napoleon Bonaparte, there were 1811-1814 belonging to the French Empire Territory Zuyderzée.

Only with the establishment of the artificial "Final dyke " ( Afsluitdijk ) in 1932 was again an inland sea. From the Zuiderzee was actually on May 28, 1932 at 13.02 clock by closing the last gate ( De Vlieter ) of the IJsselmeer dike ( " IJsselmeer "). On September 20 was officially renamed. As a result, parts of the former Zuiderzee were as a polder drained ( Zuiderzee ), including the present-day province of Flevoland, including the North-East Polder ( Noordoostpolder ) with the former islands Schokland and Urk main initiator of this work was the engineer and politician Cornelis Lely, after the Flevoländer provincial capital Lelystad is named. The largest city in Flevoland Almere means and belongs to the catchment area of Amsterdam. As an additional area for this conurbation Flevoland is more important than as agricultural land for which it was originally intended.

The name Zuiderzee can still be found on historic maps and documents to the early 20th century and is used only in historical context today. The current satellite photo, which illustrates the extent of the land acquired in the comparison, therefore, shows the IJsselmeer.