Human actions that modify terrestrial and aquatic environments contribute to unsustainability, influencing the economy and human health. Urban environments are responsible for the dispersion of pollution and nanoparticles (NPs), which can potentially harm the health of human populations and contaminate the fauna and flora of aquatic ecosystems on a global scale. The objective of this study is to analyze the dissemination of nanoparticles in Cartagena Bay, Colombia, during the strong winds/low runoff season of January 2020 and the weak winds/high runoff season of October 2021. This was accomplished using images from the Sentinel-3B OLCI (Ocean Land Color Instrument) satellite in conjunction with an analytical chemical analysis of sediments collected in the study area in a laboratory with advanced electron microscopy. It was possible to obtain, on average, a sample of suspended sediments (SSs) every 1000 m in the areas of Bocagrande, Isla de Tierra Bomba, and Playa Blanca, which were analyzed in the laboratory with X-ray diffraction (XRD) and electron transmission and scanning microscopies. Images obtained in the summer of 2020 and winter of 2021 by the Sentinel 3B OLCI satellite were selected at a distance of 1 km from each other and analyzed for the following variables: chlorophyll (CHL_NN), water turbidity (TSM_NN), and suspended pollution potential (ADG443_NN). In addition to of evaluating georeferenced maps, they were subjected to an analysis within the statistical and K-Means clustering model. The laboratory analysis of SSs showed the presence of potentially toxic NPs, responsible for contamination that may harm the health of the local population and marine ecosystems. The K-Means and satellite image analysis corroborated the laboratory analyses, revealing the source of the pollution and contamination of Cartagena Bay as the estuary located close to its center.