Because of the generally high standard of living in Europe, protein shortage is imminent. Today, protein-rich crops such as soy are imported to meet the high demand, leading to unsustainable practices. Europe, including Flanders, is committed to growing protein seeds, legumes, etc. but is far from self-sufficient in protein. SUPROSEA is framed within the Flemish Protein Strategy which sets the 40%-60% animal versus plant protein target and takes into account the limited availability of agricultural land in Flanders. Therefore, SUPROSEA focusses on aquatic protein rich biomass, i.e. different species of seaweed (green, brown and red) as they are economically and ecologically interesting organisms for the extraction of proteins, and other high-value compounts such a pigments for the food and feed industry. The main objective of the project is to identify the most promising biorefinery in terms of sustainability. The culture conditions of local seaweed will be optimized to improve the quality and quantity of the components to be extracted. Moreover, efficient ways to valorize the remaining biomass in a cascade biorefinery approach will be investigated (zero-waste approach). Different mild extraction techniques will be tested, and the residual seaweed biomass iwill be fermented to produce microbial proteins. The seaweed proteins, microbial ones and high value seaweed compounds are then characterized and tested in food and feed trials. Biorefinery process modelling will be done to obtain scaled-up data for different seaweed value chain scenarios, which will be evaluated on the basis of an integrated sustainability methodology, including life cycle analysis, biodiversity mdoelling, ecosystem services assessment, and techno-economic and market analysis. A comparison with alternative protein sources is foreseen. SUPROSEA wants to support sustainable, blue economy activities.