Zinc oxide (ZnO) is widely utilized as a mineral UV filter in sunscreen formulations due to its broad-spectrum efficacy, photostability, and acceptance by natural cosmetic certification bodies. Despite its growing use, the environmental impact of ZnO on marine ecosystems remains under debate. While zinc is an essential micronutrient for aquatic organisms, excessive concentrations of Zn compounds, particularly in nanoparticulate form, have been thought to have detrimental effects, including coral bleaching, oxidative stress, and disruptions in metabolic and reproductive functions in marine species. This review synthesizes current peer-reviewed literature on the ecotoxicological effects of ZnO, with particular emphasis on coral reef health, bioaccumulation, and trophic transfer pathways. Furthermore, real-world exposure scenarios are evaluated, incorporating field data from densely visited coastal regions and modeled environmental concentrations under worst-case use conditions.The aim of this study is to provide a comprehensive risk assessment of ZnO in sunscreen applications, balancing its recognized safety in human use with potential long-term impacts on aquatic ecosystems, thereby informing future regulatory decisions and sustainable product development.