The 1953 North Sea flood (Dutch: Watersnoodramp) was a major flood caused by a heavy storm surge that struck the Netherlands, north-west Belgium, England and Scotland. Most sea defences facing the surge were overwhelmed, resulting in extensive flooding.

The storm and flooding occurred during the night of Saturday, January 31 to the morning of February 1, 1953. A combination of a high spring tide and a severe European windstorm caused a storm tide of the North Sea. The combination of wind, high tide, and low pressure caused the sea to flood land up to 5.6 metres (18 ft 4 in) above mean sea level.

Realising that such infrequent events could reoccur, the Netherlands and the UK carried out large studies on strengthening of coastal defences. The Netherlands developed the Delta Works, an extensive system of dams and storm surge barriers. The UK constructed storm surge barriers on the Thames Estuary and on the Hull where it meets the Humber Estuary.

Flooding summary

In the Netherlands 20% of the land was below mean sea level (subsequently with the expansion of Flevoland this proportion has increased); the next-highest 30% sat at less than 1 metre (3.3 ft) above sea level. Such land relies heavily on sea defences and was worst affected, recording 1,836 deaths and widespread damage.