Brazil, the world's fifth-largest country, produces approximately 7.46 million tons of plastic waste annually (ABIPLAST 2025) , of which about 1.3 million tons (OCEANA 2024) end up in the ocean. Together with renowned partners from the Brazilian education and research, governmental, and private sectors, the PROMARES project, develops sustainable and holistic solutions to reduce marine pollution. Key measures include mapping waste sources, analyzing the socio-cultural context of marine litter generation and its transport via river systems into the marine environment, and developing and validating methods for waste assessment and prevention. PROMARES promotes the social inclusion of vulnerable groups, strengthens environmental and climate protection, and creates market incentives for sustainable waste management. A digital knowledge platform consolidates systematized data and educational content. In addition, a National Institute for Marine Litter (ML) and Circular Economy (CE) will be established to facilitate scientific exchange and technology transfer at the national and international levels. Particular attention is being paid to island and rural regions, as well as sensitive ecosystems such as the Amazon and coastal forests. The project thus strengthens Brazil's role as a pioneer in global cooperation on waste prevention and sustainable development. PROMARES is led by the Waste and Resource Management Division of TU Braunschweig and funded by the German Federal Ministry for the Environment, Climate Protection, Nature Conservation and Nuclear Safety (BMUKN) with 6 million EUR.