This paper considers the degree of competition among small and medium-sized container ports located in a multi-port gateway region. The level of port competition is evaluated by means of an analysis of the revealed preferences in the port-calling pattern of container feeder vessels deployed on their various links and routes. Unit of analysis is feeder vessel sailing legs and ports stays at/between adjacent container ports. At these ports’ terminals, ships are moored and loading and unloading of containers are performed. The vessel movement data is provided by the Automatic Identification System (AIS). A study of the principal container ports in the Oslo Fjord area is performed, measuring the actual container feeder traffic during the year o...