Coastal embayments are ecologically significant ecosystems increasingly affected by human activities and climate change pressures. This study investigated the spatial and temporal dynamics of the zooplankton community in Cam Ranh Bay under varying environmental conditions by chronically sampling in consecutive days, weeks and seasons. The bay exhibited high zooplankton diversity, with 188 species recorded across seven phyla. Arthropoda, particularly Copepoda, contributed over 65% of the total species richness. Notable changes were observed in the zooplankton community, particularly within Copepoda families, even over short periods (e.g., day or week). At a seasonal scale, the zooplankton community shifted with increased densities of larval groups during the rainy season, coinciding with a relative decrease in arthropods. Biodiversity indices indicated greater stability during the rainy season, while canonical correspondence analysis (CCA) revealed distinct seasonal relationships between species and environmental variables, such as nutrient fluxes and salinity. These findings underscore the ecological complexity of Cam Ranh Bay, providing a critical baseline for monitoring environmental changes and managing human impacts on this biodiverse ecosystem.