The study discusses the phytoplankton diversity of the Suchindram pond for a period of two years (2011-2013). Through a field survey, the population density of phytoplankton and their percentage composition observed in Suchindram pond varied much between sampling months during the study period. Among the identified groups Cyanophyceae was dominant. The next dominant groups were Chlorophyceae and Bacillariophyceae. Flagellates were recorded as the least dominant group in this pond. The lowest biomass value was recorded for Flagellates. The class Dinophyceae and Chrysophyceae were represented with minimum biomass while the class Euglenophyceae contributed to the maximum. Genera such as Ceratium and Peridinium of Dinophyceae were noticed during the northeast monsoon season in both the years of study. The class Chrysophyceae was represented with one genus with only one species i.e. Dinobryon sertularia. This species showed its appearance during southwest monsoon. The different species of each genus were distributed more frequently during summer months and with less frequency in other months. Low representation of desmids in Suchindram kulam represents the eutrophic nature of that pond. The data of Suchindram pond confirmed that the pond is already in eutrophic conditions. Among the various Phytoplankton species identified, the study area was noted for its frequent occurrence of large number of pollution indicating algae. Statistical analysis revealed that, the influence of monsoon seasons and sampling ponds on the distribution of phytoplankton groups was statistically significant.