Marine debris significantly impacts coral ecosystems, especially in regions with high biodiversity like the Sempu Island Nature Reserve in Malang, Indonesia. According to the guidelines of ReefCheck and KLHK 2020, this in-depth study looked at the types, amounts, and impacts of marine debris on coral health at five different sites close to the Pondokdadap Coastal Fishing Port. This study employs a belt transect method measuring 100 x 5 meters to systematically collect data. Our results indicate that cloth refuse is the most substantial form of waste, accounting for 84.65% of the weight of marine waste. The primary locations for this form of waste are areas with high human activity, particularly those near fishing ports. The impact of marine debris on coral reefs depends on its proximity to human activity, as it exhibits a wide range of density and composition. Millepora, a coral species characterized by its branching structure, was the most severely impacted, with damage levels spanning from 12.07% to 48.65%. This indicates its vulnerability to debris accumulation. The study determined the prevalence of a variety of waste categories, with plastic being the most prevalent. The study also focused on other inorganic waste such as packaging, fishing lines, raffia ropes, rubber (flip-flops and tires), fabric, metal (cans and metal cutlery), glass bottles, and other items, primarily in the port area. The density of debris is an important indicator of the environmental pressure exerted on coral ecosystems. Among the examined locations, the Jetty station displayed the highest concentration of inorganic debris, with a density of 0.100 items/m2. In contrast, Watu Meja Station had the lowest density of inorganic waste at 0.008 items/m2, but the highest concentration of organic waste at 0.066 items/m2. This indicates that there is less human impact but more accumulation of natural refuse. This study highlights the pressing necessity for effective marine waste management strategies, particularly near active ports like Pondokdadap, to mitigate the detrimental effects on coral reefs. We can ensure the health and sustainability of this critical marine ecosystem by reducing refuse accumulation through enhanced waste management protocols and community engagement.