Transborder Fix line transects are used by the MedSeaLitter project to assess the amount, composition, and spatial distribution of floating macro litter, bigger than 20 cm, in the Mediterranean basin. The transects, monitored all year round, cross the south east part of the Ligurian Sea, Sardinian Balearic basin, Bonifacio Strait, Central Tyrrhenian Sea, Sicilian Sardinian Channels, Adriatic Sea, and Ionian Sea. The surveyed area en-compasses a large portion of the Mediterranean Sea and falls within the MSFD marine sub-regions: the Western Mediterranean Sea, the Adriatic Sea, the Ionian and Central Mediterranean Sea.