On behalf of the Amsterdam Canal Company (A.K.M.), the North Sea Canal was dug between 1865 and 1876 according to W.A. Mr. Froger, in collaboration with J.G. Hunter. Since then, the channel has been deepened and widened five times. The first locks, the Oude or Zuidersluizen (18 meters wide), date from 1868-'76.
In the northern part of the Netherlands, the Middensluis (25 meters wide) was built in 1889-96 with an internal and external channel. An inner and outer channel also has the third lock, which was created in 1923-30, the Noordersluis (40 meters wide). At this concrete lock with rolling doors there are some concrete buildings designed by J. Emmen in functionalist style (1930). To the north of the Noordersluis a sluice was built, on which a pumping station was built in 1967-'75. Furthermore, a steel swing bridge was laid over the Middensluis and over the Zuidersluis in 1960.
