Rivers are suspected to be a main source of greenhouse gases (methane and carbon dioxide) for coastal seas, while the role of the interjacent tidal flats is still ambiguous. In this study we investigated the role of the river Elbe and the Elbe estuary as source of methane to the North Sea. With high spatial resolution by an underway degassing system and subsequent analysis by cavity ring down spectroscopy a high resolution picture of the methane distribution in surface waters and hydrographic parameters was obtained in autumn to spring 2018/19. For most areas, riverine methane was simply diluted by seawater, overlain by a strong tidal influence. However at several occasions unexpected high methane concentrations were observed. By further detailed analysis we will elucidate the role of riverine versus tidal impact on the methane flux from the coastal North Sea