Duisburg on the Rhine is stated as the largest inland harbour in the world.[1][2]
US Regulations
Title 33 of the United States Code states that an inland harbor is defined as "a navigation project which is used principally for the accommodation of commercial vessels and the receipt and shipment of waterborne cargoes on inland waters."[3]
References
↑Standardization of Ships and Inland Waterways for River/sea Navigation. Bruxelles: PIANC. 1996. p.26. ISBN978-2-87223-074-7.