The St. Elizabeth's flood of 1421 was a flooding of the Grote Hollandse Waard, an area in what is now the Netherlands. It takes its name from the feast day of Saint Elisabeth of Hungary which was formerly 19 November.

It ranks 20th on the list of worst floods in history.

During the night of 18/19 November 1421 a heavy storm near the North Sea coast caused the dikes to break in a number of places and the lower-lying polder land was flooded. A number of villages were swallowed by the flood and were lost, causing between 2,000 and 10,000 casualties. The dike breaks and floods caused widespread devastation in Zeeland and Holland.



The Zuiderzee or Zuider Zee ( ZY-dər ZEE, -⁠ ZAY, also US: ZOY-dər ZAY, Dutch: [ˌzœydərˈzeː] (listen); old spelling Zuyderzee or Zuyder Zee) was a shallow bay of the North Sea in the northwest of the Netherlands, extending about 100 km (60 miles) inland and at most 50 km (30 miles) wide, with an overall depth of about 4 to 5 metres (13–16 feet) and a coastline of about 300 km (200 miles). It covered 5,000 km2 (1,900 sq mi). Its name is Dutch for "southern sea", indicating that the name originates in Friesland, to the north of the Zuiderzee (cf. North Sea). In the 20th century the majority of the Zuiderzee was closed off from the North Sea by the construction of the Afsluitdijk, leaving the mouth of the inlet to become part of the Wadden Sea. The salt water inlet changed into a fresh water lake now called the IJsselmeer (IJssel Lake) after the river that drains into it, and by means of drainage and polders, an area of some 1,500 km2 (580 sq mi) was reclaimed as land. This land eventually became the province of Flevoland, with a population of nearly 400,000 (2011).