The European Digital Twin Ocean (EU DTO) is a crucial asset to addressing the pressing societal challenges posed by ocean change and the first demo of the pre-operational platform is presented below through its five main pillars, each with a dedicated page. This first demo will also be presented live at the Digital Ocean Forum 2024, to diverse stakeholders including European Commissioner Iliana Ivanova of the EC Directorate-General for Research and Innovation (DG RTD). This milestone will fulfil a key commitment made by European Commission President Ursula von der Leyen, who first announced the EU DTO at the One Ocean Summit in Brest, France in February 2022. Aligning with the EU Green Deal and the UN Decade of Ocean Science for Sustainable Development, the EU DTO exemplifies Europe's commitment to developing innovative scientific tools to revolutionise the approach to addressing the multi-faceted challenges facing the Ocean.