This study aimed to identify ocean-and land-based sources of nutrients to the coral reef communities surrounding the Southern Caribbean islands Aruba, Bonaire, and Curaçao. The composition of water masses around these islands were assessed to depths up to 300 meters and three distinct overlying water masses were identified, separated by mixing zones. A fluctuating pycnocline separating surface from deeper (> ~50 m) water indicated the presence of internal waves. Nutrient profiles were typical of tropical waters with oligotrophic waters occurring above the pycnocline and a deep chlorophyll maximum (DCM) just below it (~65 m). Concentrations of dissolved nutrients differed among islands. Inorganic nitrogen (DIN) and phosphate concentrations were respectively lowest around Bonaire and Curaçao. The spatial distribution of chlorophyll-a (indicative of phytoplankton abundance), rather than nutrient concentrations, suggested the presence of higher-than-average nutrient concentrations in islands with higher population densities, near urbanized/ industrial areas, and near upwelling areas.