A port that is auxiliary to another port further inland which cannot be reached by very large ships is described as

The term used to describe a port that is auxiliary to another port further inland which cannot be reached by very large ships is "a river port". A river port is a port that is located on a river and is used for the loading and unloading of cargo from ships. River ports are usually smaller than seaports and are often used for transporting goods to and from inland areas that are not accessible by large ocean-going vessels. River ports are important for trade and commerce in many parts of the world, as they provide a means of transport for goods and commodities that cannot be easily transported over land.