The Port of Rotterdam is the base of the city's economy. Located in the heart of Europe's industrialized, highly-populated triangle of the German Ruhr district, Paris, and London, the Port of Rotterdam is strategically positioned on the world's busiest sea. It is an important distribution point for products going all over inland Europe. The Port of Rotterdam also has a busy petrochemical industry and several oil refineries. Crude oil arrives by sea to be processed and delivered to areas in The Netherlands, Germany, and Belgium.