From October 2020 to June 2021 the Surfing for Science project engaged volunteers to collect scientific samples on floating microplastics in nearshore waters of the NW Mediterranean Sea. The data presented here includes all data on particle counts, sizes, shapes, colors and chemical composition of the plastics found, including concentrations for each of the investigated locations. A subset of 285 particles were chemically identified to confirm the chemical identity of the particles found. Almost 25,000 plastics were identified and characterized and were mostly microplastics (< 5 mm in length). The results provide important support for trappping of microplastics in the nearshore, which is subject to seasonal variability associated to natural and anthopogenic forcing. The data presented here can be further integrated with other studies (e.g. modelling) to understand the sources, pathways and sinks of microplastics in the global ocean.