The Manzanillabeach in Cocos Bay, Trinidad is a barrier beach that protects the freshwaterNariva Swamp from the marine environment of the Atlantic. The Manzanilla beachis a very dynamic system owing to the open bay morphology, and its exposure tothe Atlantic Ocean. This study evaluated thespatial and temporal morphological and sedimentological characteristics,alongside hydrodynamic conditions operating on the beach. This studyinvestigates the beach’s response to tidal cycles diurnally, from spring toneap tide, and seasonally. Data from nine sites during the period December 2005to September 2007 are analyzed. Coastal parameters such as beach profiles,littoral data and sediment samples were obtained using standardgeomorphological techniques. The beach volumetric changes that occurred overthe tidal cycles are also quantified. Results indicate that wave height andwave energy were good predictors of beach change. The study showed that erosionwas linked to rising tide and accretion to falling tide diurnally. Erosionoccurred during spring tide conditions and accretion dominated during neaptides. Seasonally more erosion occurred in the winter period (dry season) andbeach changes in the summer period (wet season) were controlled by theformation and migration of bars.