The mastermind behind the Zuiderzee works was Cornelis Lely (1854-1929). During his terms as Minister of Transport and Water Management, he developed plans to enclose the Zuiderzee – a huge bay of the North Sea covering about 5,000 km2 - and create large polders in the area. He strongly advocated his own ideas, but it needed severe floods along the Zuiderzee shores in 1916 before his plans were finally approved.
The implementation of Lely’s project started in 1927 with the closure of the Zuiderzee by building a 32 km long dike between the provinces of North Holland and Friesland, resulting in a giant lake: the IJsselmeer. The construction of the Afsluitdijk was finished in 1932 (see image below).
The next image shows an updated plan. The Wieringer Polder is called NW Polder in that, the Hoornsche Polder is enlarged and now called ZW (South West) Polder, and plans for a NO and SO (North resp. South East) Polder have appeared. The area of the Noordoostpolder was first reclaimed; the drainage was finished in 1940. Works on the ZW polder started the year after by building a 2 km long dike north of the small island of Marken, but the works had to be interrupted under the German occupation in World War II.
But the works on the planned ZW polder – meanwhile called Markerwaard, after the island of Marken - were never resumed. In 1981, planned area for reclaiming was revised from 600 km2 to 410 km2, but engineers couldn’t decide if additional land was really needed, and if agricultural use really was more important than the recreational value of the lake.
Discussions went on for over twenty years and the money for the project was reserved for almost a century since Lely's initial plans, until finally in 2003 it was decided not to build the Markerwaard.
In 2016 however, engineers have begun to create the Marker Wadden; a group of small islands in the Marker lake. No human occupation is planned for these islands, they should rather serve as a nature reserve.
Fun fact: The American Society of Civil Engineers declared the Zuiderzee works, together with the Delta Works in the province of Zeeland, as among the Seven Wonders of the Modern World.