Waterborne transport, which is considered as a way of achieving a more sustainable transport system, is strongly dependent on other modes for final deliveries and first collections. Therefore a major issue is the efficiency of waterway terminals. This paper aims at explaining how inland waterways terminals can facilitate flows of goods using the academic framework of "fluidity" and "fixity" introduced by a few authors. As shipments require fluidity and face fixity constraints, inland waterways terminals should optimize flows of goods within a logistics network dealing with those requirements and constraints. The first part provides details of analytical tools based on the issues of fluidity and fixity; it defines several kinds of friction conflicting with fluidity. The second part details oppositions and accommodations between fluidity and fixity illustrated by the example of the Ports of Paris