This paper presents techniques for interactive visualization of the Regional Ocean Modeling System (ROMS), a free-surface, terrain-following coordinate ocean circulation model. We have designed an interactive visualization program that allows a casual user to control the forcing conditions applied to ROMS using a graphical user interface and observe the results in real-time. We modified portions of ROMS to facilitate user interaction with a Chesapeake Bay model. In order to achieve real-time interactive visualization, a low-resolution computational grid of the Chesapeake Bay was employed and a variety of techniques were utilized to achieve appealing visualizations similar to those created from high-resolution models. Texture mapping and alpha-channel blending were used to create a smooth boundary of the bay and filtering applied to adjacent grid points eliminates aliasing. The integrated simulation and visualization environment allows a user to control wind speed and direction along with the rate of flow from the rivers that feed the bay. It also provides visualizations of water height, velocity, salinity across horizontal and vertical planes, and particle tracking. Many interesting oceanographic phenomena can be demonstrated with the interactive program, making it a tool that facilitates oceanographic teaching and research.