Landmark Europe
Afsluitdijk
The Afsluitdijk is a long wall of earth in the Netherlands. It keeps the sea out, and a road runs along its top!
The Afsluitdijk is a dike 32 kilometers long in the Netherlands. It runs between the provinces of North Holland and Friesland and closes off the IJsselmeer lake from the Wadden Sea. Its last gap was closed on 28 May 1932, and for more than 90 years it has helped protect a large part of the country from floods.
The Afsluitdijk, a 32 km dike between North Holland and Friesland, has separated the IJsselmeer from the Wadden Sea since its last gap, the Vlieter, was closed on 28 May 1932. Planned by the engineer Cornelis Lely, it carries the A7 motorway and two sluice complexes. Rijkswaterstaat completed a full strengthening of the dike in 2026.
Photo: C messier, CC BY-SA 4.0, via Wikimedia Commons
Discover the Afsluitdijk
The Afsluitdijk is in the Netherlands, a country in Europe.
It is a long bank of land. The sea is on one side, and a lake is on the other.
The Afsluitdijk is a dike, a long bank built to hold back water. It stretches 32 kilometers between North Holland and Friesland, in the north of the Netherlands.
On one side is the salty Wadden Sea. On the other side is the IJsselmeer, a lake of fresh water. Rijkswaterstaat, the Dutch water agency, says the dike literally closes the IJsselmeer off from the Wadden Sea.
Rijkswaterstaat describes the Afsluitdijk as a 32 km dike between North Holland and Friesland that literally closes the IJsselmeer off from the Wadden Sea.
For more than 90 years it has served as a flood defense, with an important task in protecting a large part of the Netherlands from flooding. The IJsselmeer behind it is a major freshwater reserve, used for farming and drinking water.
- Where
- Between North Holland and Friesland, Netherlands
- Length
- 32 km
- Closed off
- 28 May 1932
- Road
- A7 motorway
Closing the Zuiderzee
An engineer named Cornelis Lely made the first plans for the dike.
The last gap was closed in 1932. The sea there became a lake!
People had ideas for closing off the Zuiderzee as early as the 1600s, but they only became serious in the late 1800s. In 1891 the young engineer Cornelis Lely drew up the first plans for the Afsluitdijk, and in 1918 the Zuiderzee Act was passed.
On 28 May 1932, the last gap, called the Vlieter, was closed. From then on, the Zuiderzee was called the IJsselmeer.
Rijkswaterstaat records that ideas for closing the Zuiderzee date from the 17th century but became serious only at the end of the 19th. In 1891 the young engineer Cornelis Lely worked out the first plans; in 1913, as minister of water management, he put the project on the cabinet's agenda, and Lely's Zuiderzee Act was passed in 1918. A flood struck the Zuiderzee area in 1916.
Work to close the Zuiderzee began in 1920. At 1:30 p.m. on Saturday 28 May 1932, the last gap, the Vlieter, was closed, and the Zuiderzee became the IJsselmeer. A year later, traffic could cross the dike on what is now the A7.
A dike, a road and sluices
A busy highway runs along the dike. Cars and trucks cross it every day.
Gates in the dike let extra lake water flow out to the sea.
The A7 motorway runs along the Afsluitdijk, linking Friesland and North Holland. Thousands of vehicles cross it every day.
Two groups of sluices are built into the dike: the Stevin sluices at Den Oever and the Lorentz sluices at Kornwerderzand. They let extra water flow out of the IJsselmeer into the Wadden Sea. Locks at both places let boats pass between the lake and the sea.
Rijkswaterstaat explains that the dike must be high and strong enough to resist the sea in the most extreme conditions. Its two sluice complexes, the Stevin sluices at Den Oever and the Lorentz sluices at Kornwerderzand, discharge surplus water into the Wadden Sea, much of it from the IJssel, a branch of the Rhine.
Shipping locks at Den Oever and Kornwerderzand let ships and pleasure boats reach the Wadden Sea; Rijkswaterstaat calls them very important for reaching the north, center and east of the Netherlands. The A7 on the dike carries thousands of vehicles a day between Friesland and North Holland.
Towers, a lookout and a river for fish
There is a lookout tower on the dike. From the top you can see the sea and the lake!
A new river is being made through the dike to help fish swim between the sea and the lake.
Rijkswaterstaat says the dike made a unique view: a straight sea dike between the Wadden Sea and the IJsselmeer, with buildings and lifting towers by the architect Roosenburg and a lookout tower, the Vlieter monument, by the architect Dudok.
The dike used to block fish that swim between salt and fresh water. A fish passage was built at Den Oever, and a fish migration river several kilometers long is being made through the dike at Kornwerderzand.
Rijkswaterstaat calls the Afsluitdijk a strong example of Dutch hydraulic engineering, known at home and abroad, and lists its landscape: the classic sea dike as a straight line between the Wadden Sea and the IJsselmeer, the buildings and lift towers of architect Roosenburg, and the Vlieter monument, a lookout tower by architect Dudok.
Because the dike proved an impassable barrier for fish moving between fresh and salt water, a fish passage was built west of the lock at Den Oever, and a fish migration river several kilometers long is being built through the dike at Kornwerderzand.
- Planned by
- Cornelis Lely (1891)
- Sluices
- Den Oever and Kornwerderzand
- Lookout tower
- Vlieter monument (architect Dudok)
- Strengthened
- 2019–2026
Sea on one side, lake on the other
In this photo, cars drive along the dike. The sea is on the left and the lake is on the right.
The road goes on and on, almost to the sky!
This photo was taken on 26 August 2016 from the lookout tower, looking northeast toward Friesland. The Wadden Sea is on the left and the IJsselmeer on the right, with the A7 motorway running straight along the dike between them.
In 2026, Rijkswaterstaat finished strengthening the whole 32 kilometers of the dike, and a new pumping station and new sluices opened on 1 October 2026.
The photograph (26 August 2016, by C messier, a Commons Quality image) looks north-eastward toward Friesland from the monument tower: the Wadden Sea at the left, the IJsselmeer at the right, the grassy sea dike and a parking area beside the A7 motorway.
Rijkswaterstaat reports that the large-scale strengthening and renewal of the dike, started in 2019, was completed when a new pumping station and new discharge sluices at Den Oever were officially opened on 1 October 2026. The dike was raised and reinforced along its full 32 km, and new storm-surge locks were built at Den Oever and Kornwerderzand.
Amazing facts
-
When the dike was closed, a part of the sea got a new name!
After the last gap was closed in 1932, the Zuiderzee was called the IJsselmeer.
With the closing of the Vlieter on 28 May 1932, the Zuiderzee was renamed the IJsselmeer.
-
Fish are getting their own river through the dike!
A fish migration river several kilometers long is being built right through the dike, so fish can swim between the sea and the lake.
The fish migration river being built at Kornwerderzand, several kilometers long, crosses the dike to reconnect the Wadden Sea and the IJsselmeer for migrating fish.
-
The last gap in the dike was closed at half past one in the afternoon!
The last gap, the Vlieter, was closed at 1:30 p.m. on Saturday 28 May 1932.
Rijkswaterstaat dates the closing of the last gap, the Vlieter, to Saturday 28 May 1932 at 13:30.
Words to know
- dike
- a long bank of earth built to hold back water
- sluice
- a gate that controls how much water flows through
- lock
- a section of waterway with gates, used to move boats between different water levels
- fresh water
- water that is not salty, like the water in most lakes and rivers
- flood defense
- a structure built to keep floodwater away from land
- fish migration
- fish traveling from one kind of water to another, for example from the sea to a lake
Discovery challenge
-
In which country is the Afsluitdijk?
The Afsluitdijk runs between North Holland and Friesland, in which country?
Which country's water agency, Rijkswaterstaat, looks after the Afsluitdijk?
- The Netherlands
- Norway
- Nepal
Show the answer
The Netherlands
The Netherlands!
The Netherlands.
The Netherlands.
-
How long is the Afsluitdijk?
How long is the Afsluitdijk?
What length does Rijkswaterstaat give for the Afsluitdijk?
- 32 kilometers
- 3 kilometers
- 320 kilometers
Show the answer
32 kilometers
32 kilometers!
32 kilometers.
32 km.
-
What new name did the Zuiderzee get after the dike was closed?
What was the Zuiderzee called after its last gap was closed in 1932?
What did the Zuiderzee become once the Vlieter was closed?
- IJsselmeer
- North Sea
- Wadden Sea
Show the answer
IJsselmeer
The IJsselmeer!
The IJsselmeer.
The IJsselmeer.
-
Who made the first plans for the dike?
Which engineer drew up the first plans for the Afsluitdijk in 1891?
Which engineer, later a minister, worked out the first Afsluitdijk plans and gave his name to the Zuiderzee Act?
- Cornelis Lely
- Vincent van Gogh
- Rembrandt van Rijn
Show the answer
Cornelis Lely
Cornelis Lely!
Cornelis Lely.
Cornelis Lely.
-
In which year was the last gap in the dike closed?
In which year was the Vlieter, the last gap, closed?
In which year did the closing of the Vlieter turn the Zuiderzee into the IJsselmeer?
- 1932
- 1832
- 1992
Show the answer
1932
1932!
1932.
1932 (28 May).
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For parents & teachers
What children will learn
- Explain how a dike protects land from the sea.
- Describe the difference between salt water and fresh water.
- Explain why old structures sometimes need to be made stronger.
Recommended ages: 4 to 17 · About 15 minutes
Talk about it
- Why would a country close off part of the sea?
- How can people help fish get past a dike or a dam?
- Why might a dike built in 1932 need to be raised today?
Try at home or in class
- In a tray, build a wall of sand or clay between salty water and fresh water, then add a small gate to let water through.
- Find North Holland, Friesland, the Wadden Sea and the IJsselmeer on a map of the Netherlands.
Key vocabulary: dike, sluice, lock, fresh water, flood defense, fish migration
Where these facts come from
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Afsluitdijk , Rijkswaterstaat
- Project Afsluitdijk , Rijkswaterstaat
- Versterking Afsluitdijk afgerond: gemaal en nieuwe spuisluizen officieel in gebruik , Rijkswaterstaat
- File:Afsluitdijk 1031.jpg , Wikimedia Commons
- Wikimedia Commons , Wikimedia Foundation (Per file (public domain, CC0, CC BY or CC BY-SA); see each media record)
Checked, not yet human-reviewed. Last updated November 1, 2026. Spotted a mistake? Tell us.