In the frame of the E.U. project Envri+, task 4.2 of the WP4 is organized around the development of a joint pilot experiment on a RIs platform at sea to measure methane transfer from the seafloor to the atmosphere. The pilot experiment will develop around joint monitoring strategies for methane detection at various levels starting from the seafloor and moving across the water column, the water/air interface and the atmosphere. The Romanian sector of the Black Sea is the selected location. This area hosts a large number of emission sites of methane-rich gases, from the continental shelf to the deepest part of the basin. It is consequently a good candidate for investigating the fate of marine methane, from the sedimentary column to the atmosphere by combining the expertise and technologies of six EU teams. The methodology applied integrates (1) sampling from the three spheres (lithosphere, hydrosphere and atmosphere) for laboratory measurements of methane concentration by well-proven standard methods together with ?¹³C-CH₄ analysis, (2) in situ measurements of methane concentration and ?¹³C-CH₄ into the water column and the atmosphere, and (3) the deployment of a seafloor observatory for a short monitoring period (4-5 days) to evaluate the temporal variability of gas fluxes.