A geographic information system (GIS) was developed for retrieval and display of hydrodynamic and water quality data. To establish such a system, two of the most important challenges are: (1) to establish a rigorous model which captures the three-dimensional and continuously changing characteristics of marine data and (2) to develop interpolation techniques to accommodate for the temporally and spatially scattered distribution of collected data. The developed system not only bridges together a GIS and a database of various physical, chemical and biological geographically based data for efficient retrieval and management of information, but also incorporates advanced display tools designed specifically for marine data. The initial intention of extending GIS for marine application is to mitigate the deteriorating water quality situation in the Pearl River Estuary (PRE).