IJmuiden (ˌɛi̯ˈmœy̯də(n)) is a port city in the Dutch province of North Holland. It is the main town in the municipality of Velsen which lies mainly to the south-east. Including its large sea locks, it straddles the mouth of the North Sea Canal to Amsterdam. To the south it abuts a large reserve of plant-covered dunes, the Zuid-Kennemerland National Park. The city is on the south bank; the north bank is otherwise a steel plant and Velsen-Noord.
It is north northwest of Haarlem which is due west of Amsterdam.
The port is a deepwater port suited to fully laden Panamax ships, and fourth port of the Netherlands.
The internal capitalization within IJmuiden is as IJ is a digraph in modern Dutch so in some typefaces recognised as a ligature which places it in one typed or handwritten space.
In the Roman era, the district was already inhabited, and archaeological finds at the impoldered lake of Wijkermeer indicate there was a North Sea port of some regional importance built here. Present day IJmuiden includes four harbors: the vissershaven (Ship's code IJM), a fishing dock (visafslag), the haringhaven, the IJmondhaven and the Seaport Marina IJmuiden, a harbour for pleasure craft. IJmuiden became the largest fishing port of the Netherlands after the island of Urk became closed in by the Afsluitdijk. The town suffered heavy damage and demolition during World War II, because of its maritime importance.
Before IJmuiden was built, the area was known as Breesaap, a desolate plain where a handful of farming families strove to make a living.
Plans to connect Amsterdam with a canal to the North Sea, with its mouth in this area, had been drawn up already since 1626, but were only set into motion in the 19th century, when in 1851 the whole area was sold to the entrepreneurs Bik and Arnold. Ground was broken on 8 April 1865.
IJmuiden is the newest city in North Holland. It was founded on 1 November 1876, when the North Sea Canal was officially opened by William III of the Netherlands, shortcutting Amsterdam's harbours' passage to the sea.