The Port of Rotterdam is the largest seaport in Europe, and the world's largest seaport outside of East Asia, located in and near the city of Rotterdam, in the province of South Holland in the Netherlands. From 1962 until 2004, it was the world's busiest port by annual cargo tonnage. It was overtaken first in 2004 by the port of Singapore, and since then by Shanghai and other very large Chinese seaports. In 2020, Rotterdam was the world's tenth-largest container port in terms of twenty-foot equivalent units (TEU) handled. In 2017, Rotterdam was also the world's tenth-largest cargo port in terms of annual cargo tonnage.

A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manchester and Duluth; these access the sea via rivers or canals. Because of their roles as ports of entry for immigrants as well as soldiers in wartime, many port cities have experienced dramatic multi-ethnic and multicultural changes throughout their histories.