GEO Gesellschaft für Energie und Oekologie mbH plans the erection of the windfarm “DanTysk'” in the exclusive economic zone (EEZ) at the Danish border in the German Bight. The planning area was chosen at a distance of more than 70 km from the island of Sylt. It is not only outside the visibility of landbased locations but also outside Natura 2000 conservation areas (fauna, flora and bird habitats). 80 windenergy converters are planned with an installed total performance of 400 MW as a first step. Within the approval procedure OECOS worked out information material about the surrounding marine environment and certain cause and effect relationships. Furthermore all plan related effects of the windfarm on subjects of protection and human interests which could cause impairments during the construction phase and operation were summarized. The OECOS team advised GEO mbH on-site at the coordination of the regular environmental impact assessment studies and summarized the individual examinations in general reports. Among others the combination of the EIA report and FFH compatibility study as well as the final report of the baseline studies have been completed by OECOS.