This chapter examines whether the concept of maritime region provides a valid framework for the analysis of ports and maritime networks and explains how the better understanding of the regional dimension contributes to existing port and maritime studies. It then explores the classical and recent definitions of the concept of region in geography and social sciences in general, before embarking on more empirical studies of regions in transport and mobility studies as well as in the specific area of port and maritime studies. Based on such a background, the chapter proposes an analysis of the evolution of maritime links within the Mediterranean basin and two other regions, namely the Caribbean basin and East Asia, based on container flows over the last 30 years. The focus on vessel movements as a way of verifying the topological and functional consistency of maritime regions had various outcomes at different levels.