With the unveiling of ForceNet, the Navy's architectural framework for how naval warfare is to be conducted in the information age, much of the technological focus has been placed on Web technology. One of the most promising technologies is Web services. Web services provide for a standard way to move and share data more reliably, securely, and quickly. The capabilities imbedded in Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP) can merge previously disparate systems into one integrated environment. Already proven successful in the administrative realm, wide-area networks such as the Secure Internet Protocol Network (SIPRNET) have become secure and reliable enough to pass data between systems and units to support tactical operations. The Modeling, Virtual Environments and Simulation (MOVES) Institute at the Naval Postgraduate School is currently working to extend these precepts into the modeling and simulation world under the Extensible Modeling and Simulation Framework (XMSF) project. By leveraging existing Web service technology, warfighters at the \"tip of the spear\" can have access to previously unrealized amounts of tactically-relevant data, analysis, and planning tools. The goal of this thesis is to apply the XMSF and Extensible 3D (X3D) graphics to the field of sonar visualization. Undersea warfare is a complex operation that requires a continuous and detailed analysis of the acoustic environment. Tactical sensor employment without a firm understanding of the complete undersea picture can lead to fatal consequences. The Navy has spent significant resources to develop training systems and tactical decision aids in an effort to integrate training, rehearsal and execution. Unfortunately, many of the high-resolution analysis tools that can provide high-resolution sonar prediction results are not easily accessible to the fleet. By taking advantage of Web services and XMSF technology, warfighters will need only access to the network to be able to pull real-time environmental analysis data from large databases, remotely run sonar prediction models on supercomputers, and view detailed three-dimensional (3D) virtual worlds that visualize the undersea picture.