A detailed study of the Dinophyceae was carried out for a period of two years. Of the 103 species recorded and described about 20 are oceanic elements. Some of them such as Ornithocercus (5 spp.), Ceratocorys horrida, Ceratium praelongum, C. ranipes, C. teres and Dinophysis cuneus are indicators of upwelling. Species diversity index with related parameters namely, species richness and evenness showed maximum values during summer seasons. An inverse relationship between species diversity and dominance was noticed. Intermediate salinity values were found to be favourable to dinoflagellates. Species belonging to other major geographical regions have been recorded.