Ocean Data View (ODV) is a freeware package for the interactive exploration and graphical display of multi-parameter profile or sequence data. Although originally developed for oceanographic observations only, the underlying concept is more general, and data or model output from other areas of geosciences, like for instance geology, geophysics, geography and atmospheric research can be maintained and explored with ODV as well. The data format of ODV is designed for dense storage and direct data access, and allows the construction of very large datasets, even on affordable and portable hardware. ODV supports display of original data by colored dots or actual data values at the measurement locations. In addition, two fast and reliable variable-resolution gridding algorithms allow color shading and contouring of gridded fields along sections and on general 3D surfaces. A large number of derived quantities can be selected and calculated online. These variables are displayed and analyzed in the same way as the basic variables stored in disk files. ODV runs on PCs under Windows and on UNIX workstations under SUN Solaris. The software and extensive sets of coastline, topography, river-, lake- and border outlines as well as various gazetteers of topographic features are available at no cost over the Internet. In addition, the electronic atlas eWOCE that consists of oceanographic data from the World Ocean Circulation Experiment (WOCE) is also available free of charge over the Internet. A gallery of prepared plots of property distributions along WOCE sections provides a quick overview over hydrographic, nutrient, oxygen and transient tracer fields in the ocean and, apart from the scientific use for oceanographic research, can serve as tutorial material for introductory or advanced courses on oceanography.