The Hellenic Navy is confronted with a set of mission-related challenges that can not be efficiently supported by existing information systems. However, the transition to more modern information systems needs to fulfill a basic principle of command and control, "unity of purpose". This thesis uses the unifying concept of information architectures to identify some desired characteristics for future HN information systems. Two real-life projects are reviewed to substantiate the analytical suggest ions borrowed by the client-network, or network-centric architectural paradigm. The "SeaNet" project is used to show the feasibility and utility of extending internet technologies to the maritime environment. The "Baffle Force e-mail" project is presented as a pilot program for the introduction of TCP/IP based data exchange between units at sea. At the concluding Chapter, a set of recommendations is made for the transition to a network-centric information architecture for the Hellenic Navy and the development of internetworking capabilities over seawater.