The design of modern Information Fusion (IF) systems involves a complex process to achieve the requirements in the selected applications, especially in domains with a high degree of customization. In general, an advanced fusion system is required to show robust, context-sensitive behavior and efficient performance in real time. It is necessary to exploit all potentially relevant sensor and contextual information in the most appropriate way. Among modern applications for IF technology is the case of surveillance of complex harbor environments that are comprised of large numbers of surface vessels, high-value and dangerous facilities, and many people. The particular conditions and open needs in the harbor scenario are reviewed in this paper, highlighting research opportunities to explore in the development of fusion systems in this area.