An experimental GIS for the Island of Sicily was developed, aiming at the classification of some traits of both the marine and terrestrial environment in coastal zones. The GIS integrates data generated by remote sensors and conventional cartographic data. Parameters describing the marine environment, at the regional scale, were derived from time series of composite chlorophyll-like pigment concentration images generated by the Coastal Zone Color Scanner (CZCS) in the period 1979 - 1985, and of composite sea surface temperature images generated by the Advanced Very High Resolution Radiometer (AVHRR) in the period 1982 - 1985. Other auxiliary data, such as bathymetry and maps of hydrological basins, rivers, elevation, and reservoirs were selected to complement the low-resolution satellite data set and introduced in the regional GIS. At the local scale (Simeto river basin and Gulf of Catania), parameters describing essential coastal water constituents and vegetation were derived from TM data (1985 and 1994). The ancillary data set integrated with the high-resolution images includes information about physical and biological components of the local coastal environment (i.e. geographic, geological, geomorphologic, sedimentary and vegetation outlines). Examples of the synergistic use of such data, at various space/time scales, include assessing the impact of runoff from hydrological basins on the marine ecosystem, sediment transport and coastal evolution, vegetation cover.