Marine plastic waste (MPW) is a complex and contaminated waste stream that poses significant challenges for recycling with traditional methods. The CUPOLA project aims to address this issue by developing integrated, carbon-neutral processes for sorting and converting MPW into valuable chemicals, carbon materials, and functional products. This initiative involves separating MPW into PET-rich, polyolefin-rich, and polyamide-rich fractions, followed by customised recycling and upgrading pathways, all supported by process modelling and environmental assessments. The conversion of PET-rich municipal plastic waste can produce high-value intermediates for road applications. Glycolysis enables the recovery of terephthalic acid in high purity, whereas aminolysis yields terephthalamide-based compounds with reactive hydroxyl and amide functionalities, making them suitable for bitumen modification. Furthermore, the reported results indicate that the glycolysis route has a favourable environmental performance, highlighting its potential as a sustainable method for PET valorisation. The catalytic conversion of polyolefin-rich MPW, showed strong potential for producing BTX aromatics, hydrogen, and carbon nanotubes. Ex-situ catalytic pyrolysis achieved conversion efficiencies above 98 wt. %, with aromatic compounds dominating the liquid fraction, while catalytic vapour deposition routes enabled the simultaneous generation of hydrogen and carbon nanomaterials. Additionally, MPW-derived products can serve as functional carbon materials and CO2 capture media. The PA-rich MPWs were valorised for fibre regeneration and the production of nitrogen-rich carbonaceous materials. Beyond the technical results, CUPOLA is fundamentally a collaboration- and knowledge-transfer-driven project. It was designed as an international, interdisciplinary and intersectoral programme connecting universities across Europe and Asia to develop long-term research cooperation in marine plastic waste recycling. A core project objective is the transfer of knowledge through staff exchanges, training schools, workshops, enabling mutual learning across disciplines such as waste sorting, chemical recycling, process modelling, life cycle assessment, and techno-economic analysis. In this sense, CUPOLA is not only developing new valorisation routes for MPW, but also building the research capacity, shared expertise, and collaborative framework needed for their future implementation.