During the period of study, the average sea surface temperature (SST) and average sea surface salinity (SSS) were 29.45℃ and 32.9, respectively (Table 1). SST increased from the north part to the south part; but SSS was relatively homogeneous in most areas except in the Vietnam coast and Mekong River Estuary (Fig. 2). It showed a significant lower SST and a significant higher SSS values in the upwelling region off Vietnam. The lowest SST (27.25℃) and the highest SSS (33.85) all occurred at Sta. 8. The lowest SSS occurred at Sta. 16 (32.22) nearby the Mekong River Estuary.