The Oceanographic Visualization Interactive Research Tool (OVIRT) was developed to explore the utility of scalar field volume rendering in visualizing environmental ocean data and to extend some of the classical 2D oceanographic displays into a 3D visualization environment. It has five major visualization tools: cutting planes, minicubes, isosurfaces, sonic-surfaces, and direct volume rendering. The cutting planes tool provides three orthogonal cutting planes which can be interactively moved through the volume. The minicubes routine renders small cubes whose faces are shaded according to function value. The isosurface delineate the extent and axis of the shallow and deep sound channels. The direct volume rendering (DVR) techniques give a global view of the data. Other features include the ability to overlay the shoreline and inlay the bathymetry. There are multiple colormaps, an automatic histogramming feature to allow computationally expensive functions to be executed on remote machines.