The North Sea Canal
The canal which gave Amsterdam a more direct access to and from the North Sea
The North Sea Canal is an important piece in the overall puzzle to resolve the silting of the IJ inlet in the North of Amsterdam, letting the city keep its function as an important harbour. Without it, the area around the Oosterdok would surely have developed in a different way, as it presents itself nowadays.
The construction of the North Sea Canal began in 1865 to connect Amsterdam directly to the North Sea in the West. For this purpose, the IJ was poldered from its South and North banks up to the final canal route and closed off at both ends by locks. Poldering means, that land mass was gained from draining huge areas, formerly covered by water. After the canal locks were completed, the Oosterdok lost its sheltered character. The Oosterdoksluis had become superfluous.
The part of the IJ, that flows now into the Markermeer (formerly Zuiderzee) in the East, is called the "Buiten-IJ" (Outer IJ), the rest of the waterway goes by the name of "Binnen-IJ" (Inland IJ). The Southern tip of the Markermeer was given the name Ijmeer. On the map the initial extent of the IJ can be seen, together with the vast water masses which surrounded Amsterdam around 1850.
By comparing the two maps, before and after the construction, it is clear how the huge water surface was greatly restricted, the course of the IJ straightened and thereby access to the North Sea created. It is also obvious that the time to reach Amsterdam by sea was greatly reduced. The areas coloured in brown represent the original extent of the Ij, before being canalised. The extensive measures had become necessary, because the historical access via the former Zuiderzee had become an insurmountable obstacle for the ever-larger ships.
In addition to the Oranjesluizen in the East, near Schellingwoude, the locks in the West on the North Sea near Ijmuiden help to maintain the water level in the North Sea Canal and prevent too much salt water from the North Sea Canal from entering the Markermeer. After several major reconstructions, the locks near Ijmuiden, with a length of 500m, a width of 70m and a depth of 18m, are now the largest in the world.