IJmuiden is a port city in the Dutch province of North Holland and is the main town in the municipality of Velsen. It is located at the mouth of the North Sea Canal to Amsterdam, and lies approximately north of Haarlem.The internal capitalization in the city's spelling is because IJ is a digraph in Dutch, and is therefore sometimes considered to be a ligature, rendering it a single letter.The port of IJmuiden is a deepwater port suited to fully laden Panamax ships, and fourth port of the Netherlands.HistoryIn the Roman era, this Velsen 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.