From the centrality view point, the port works as a hub on a wheel. This method of understanding posits that the port is the center of economic activity, and that the spokes of the wheel, or forms of intermodal transportation, should be developed as a function of the port's existence. Many ports act as hubs, and most of them are seaports. Seaports are not always the terminus of port activity however, and ports can also be viewed as intermediaries between other ports. Often times passengers and cargo are moved to other destinations as they pass through a port. Other times, cargo and people are loaded and unloaded, completely or incompletely...

In this way, ports can be seen as intermediaries between these two points (Rodrigue, Comtois, and Slack, 2009). Therefore, location is extremely important in either viewpoint. If a port is to be the final destination of cargo and people, it must also consider the motivations and needs of these two separate types of cargo when the port planners and managers are considering future port expansion and growth.
References

Rodrigue, Jean-Paul; Comtois, Claude and Brian Slack (2009). The Geography of Transport

Systems. Routledge: New York.