Towards shipping decarbonisation, the maritime industry faces multiple challenges either in terms of reducing the energy demand of ships or in exploring alternatives to the dominant conventional fossil fuels. In both cases, industry stakeholders require strong proof of the technical and financial feasibility of possible decarbonisation options in order to gradually adopt them at a large scale. Research and innovation actions are focusing on specific technologies for improving their readiness and providing respective proof or are exploring a more holistic view on the various decarbonisation options. For the latter, introducing a regional approach can be more effective. For instance, the green corridors approach offers a promising option for reducing emissions from ships on specific routes. However, this approach is considered on a case-by-case basis, failing to address larger regions. This paper attempts to systematically explore green shipping pathways for a clean energy transition in the Mediterranean Sea basin, as part of the EU-funded GreenMED project. The methodological framework is based on bottom-up approaches, capitalising on AIS data, to provide an estimation of the fuel consumption and emissions of the fleet of scope, while employing a supply chain mapping to analyse the existing and expected fuel supply chains supporting the demand of the maritime activity in the region. The scope and framework of the study is presented to set the basis for its materialisation, while also offering a view on some early insights in terms of both the supply chain and energy demand.