Macroplastic

Macroplastic is plastic debris larger than 5 mm in its longest dimension, the visible fraction of marine litter that includes bottles, bags, packaging, fishing gear, and foam. It dominates beach-litter surveys and shoreline mass, entangles marine megafauna, smothers benthic habitat, and serves as the feedstock for microplastics: UV and mechanical weathering fragment macroplastic into ever-smaller particles. The 5 mm boundary, set by GESAMP and NOAA, separates macroplastic from microplastic; intermediate items are sometimes termed mesoplastic. Discharge of plastics and garbage from ships is banned outright under MARPOL Annex V, which prohibits disposal of all plastics into the sea.