Based on monthly hydrographical survey during 1976, a description of the seasonal and spatial variation of the fundamental oceanographical parameters (Salinity, Temperature, Dissolved Oxygen and Density) around the Margarita Island is presented in the paper. Hydrographical properties of the surface layer show a notable variation during the whole year, in response to variability of the wind induced coastal upwelling process and freshwater discharge coming from the South American rivers (Orinoco and Amazona). Specifically, bigger fluctuations correspond to the sea water surface temperature pattern, with values ranging from 20 to 25 °C during the period octuber-november. Similar behaviour is showen by the surface regime, with values ranging in general from 33%. (september-octuber) to 37,4% (march-april). Water mass analysis, using T-S the diagramas, confirm the results of earlier investigations.