Plastic pollution on the Mediterranean coastline: generating fit-for-purpose data to support decision-making via a participatory-science initiative

•Participatory-science is an effective tool for generating fit-for-purpose beach litter data.•The majority of litter items are plastics accounting for 90% of all litter collected.•Single-use plastics account for a large fraction of the recorded items.•The majority of traceable marine litter items originate from shoreline sources.•The geographical position of the beaches affects the beach litter profiles.