Plastic debris is transported by ocean currents over long distances, reaching remote areas, far from its original source. In Polar Regions, microplastics (MPs) may come from local activities or be transported from lower latitudes, the former being the likely source. Although historically Antarctica was considered isolated from the global ocean, there is recent evidence of materials and organisms being transported in and out of the Southern Ocean, despite its multi-front structure. During the austral summer of 2019, beach surveys were conducted on the NW coast of the Fildes Peninsula (King George Island). The beach was characterised, and the first 2 cm of sediment from 5 quadrants (50x50 cm) along 100 m of the highest strandline were collected. Large microplastics (LMPs) and mesoplastics (MesoPs) were isolated, counted, measured, weighed and classified by shape. Polymer composition was analysed by FTIR and ageing estimated by Carbonyl Index. Persistent organic pollutants (POPs) such as OCPs, PCBs and PBDEs were also assessed. We found 293 items of LMPs (188 items) and MesoPs (105 items), with a total average density (±SD) of 234.4±166 items m -2 . Foams (124.8±72.9), Fragments (58.4±56.0) and Pellets (44.0±50.5) were the most abundant shapes. The main polymers found were Polystyrene, Polypropylene, and Polyethylene. POPs levels were below the quantitation limits (LOQs). We found pellets among the MesoPs, being this the first record for beaches in Antarctica. The presence of these primary MPs south of 62°S not only alerts about their possible direct consequences on Antarctic ecosystems, but also gives empirical evidence for the passive entry of plastic debris from lower latitudes through cross-frontal exchanges, providing new evidence of a global connectivity of the Southern Ocean. Despite increasing research, knowledge of plastics dynamics and their impact in the Southern Ocean and Antarctica is still limited but certainly necessary
