Using VTK, a visualization tool was developed for TELEMAC-2D, a hydro-informatic model used in estuarine research. The target audience was ocean scientists and computer scientists. By creating dynamic interactive environments, scientific visualization has an important role in ocean science, where large datasets with complex inter-relationships challenge meaningful analysis. Yet many researchers rely on TELEMAC's graphics post processor, although there seems to be a case for visualization to support investigation and add insight. TELEMAC-2D datasets of the Dyfi Estuary, Wales provided test data for the tool. Development of the tool included techniques to support exploration and analysis; uncertainty and validation, and computer capacity/memory management issues. Users evaluated the tool as having significant potential to deal with a complex estuarine environment. Areas of success included applicability to different computational domains; ability to complement the existing graphicsmodule; effectiveness of the user interface; apparent validity of the visualizations, and the ability to build on the framework to provide users with enhanced tools to explore and understand data.