Access to reliable and high-quality biodiversity data is crucial for evidence-based decision-making in marine conservation and policy, notably for the implementation of the EU biodiversity and climate adaptation strategies, the EU Habitats and Marine Strategic Framework directive and the Kunming-Montreal Global Biodiversity Framework (GBF). However, despite significant advances in data collection, there remain critical bottlenecks that prevent stakeholders from effectively utilising these data. Key challenges include the limited use of international and sustainable repositories, inconsistent data formats, poor metadata quality, and a lack of practical data products. To better understand stakeholders’ challenges, barriers and needs related to biodiversity monitoring data, the MARCO-BOLO (MARine COastal BiOdiversity Long-term Observations) project, funded by the EU’s Horizon Europe programme, conducted an extensive stakeholder survey. The MARCO-BOLO project seeks to enhance the use of marine biodiversity monitoring data for decision-and policymaking by addressing identified challenges contributing to data standardisation, and harmonisation, improved accessibility, pioneering new technologies, and promoting stakeholder collaboration.