The action was planned to support the further implementation of Marine Strategy Framework Directive, providing a baseline for marine litter/debris. The project was implemented with the involvement of the 10 project partners and was coordinated by Mare Nostrum and ACCOBAMS Secretariat. For more detailed information on the dataset, including abundances estimates, please contact the project coordinator (marian_paiu@marenostrum.ro) or access the webpage www.cenobs.eu. The line transect distance sampling method has been used for the survey. This method is based on a statistical approach: data are collected by observers on board of aircrafts following specific transects designed to ensure an equal coverage and representation of the study area. For birds and marine litter a strip transect was adopted. The aerial survey has covered the waters of Romania, Bulgaria, Turkey, Ukraine and Georgia (territorial waters and exclusive economic zones) following pre-defined transect lines within different blocks. The survey design has been later adjusted according to Flight Information Regions (FIRs) constraints, as this was limiting the possibility of flying in specific areas.