After a remarkable 7-year journey spanning 68,000 nautical miles and visiting 50 countries, the zero-emission laboratory vessel, Energy Observer, returned to St Malo, France. The vessel, a testament to clean energy technologies, played a crucial role in demonstrating the feasibility of hydrogen propulsion in maritime transport. Guy Saillard, a Naval Architect and key figure in the project, rejoiced in the success of the voyage and the application of his propulsion chain technologies in 'PROMETEO', Europe's pioneering electro-hydrogen catamaran. Saillard's innovative propellers, though later replaced for efficiency, showcased exceptional performance in hydrogenation and propulsion. The reunion with the Energy Observer team highlighted the successful operation of the propulsion chain, crucial for 'PROMETEO's development. The endorsement of the technologies involved signifies a significant step towards decarbonising maritime transport and embracing sustainable practices in the industry. The collaboration of companies like Green Navy in advancing clean energy solutions is essential for addressing global energy challenges and fostering a more sustainable future.