This training aims to support the establishment of monitoring programmes to address the need for quality data and effective monitoring of land and sea based sources, quantities, fate and impact of marine litter and strengthen the capacity of member countries to use an evidence-based approach to decision making in support of global initiatives, including Sustainable Development Goal 14.1. The training is based on the Guidelines for the Monitoring and Assessment of Plastic Litter in the Ocean developed by the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP).