Bruges

Burges is not located directly on the North Sea, it is an inland port connected by canals to Ostend and Zeebrugge, as well as to Ghent.

An excerpt from the article 31 facts about Bruges

At one time Bruges was a major port, even though it was not on the sea. It had a connection to it via canals. When these became sited up, it lost it. It regained it thanks to a storm in 1134, which created the natural Zwin Canal.