This chapter outline the importance of data and tools in Marine Spatial Planning (MSP), examines different aspects data and tools, general challenges and identifies how project managers, planners and implementers can support and add value to MSP projects. Data forms the backbone of any decision-making and planning process. Therefore, the type and quality of data you use in the process will directly impact the results of planning and implementation (Lodge et al., 2014; Albotoush et al., 2021). In some MSP resource material, data is also called ‘evidence,’ with the difference being that data intrinsically has no meaning for planning, but ‘evidence’ is for something relating to the planning process. Data or evidence can take many forms, including “environmental, social or economic assessments, scientific advice, analysis of planning and management measures, marine monitoring or the use of geographic information systems and the data that underpins them”. MSP data (in particular geospatial data) tends to play a role in 3 specific ways (European Commission, 2017): 1. Provides an overview of spatial distribution of human activities, marine ecosystems, and hotspots (e.g., species distribution maps, shipping density, wind areas, Marine Protected Areas (MPAs), etc.); 2. Identifies conflicts and shared space opportunities (e.g., user conflicts between fishers and shipping areas); 3. Allows spatial exploration of future economic and climate scenarios (e.g., different predictions under climate change scenarios). Alongside the importance of available, usable, and good quality data for MSP, there is a need for planning and support tools to utilize the data fully. Tools are used for (i) spatial evaluation tools for assessment, impact and conflict analysis; (ii) guidance on how to factor ecosystem services into plans; (iii) analysis of the spatial dimension of future trends and related future scenario planning (European Commission, 2017). Several tools exist but tend to be industry-specific and are therefore unable to integrate across sectors or are model-based, making it hard for stakeholder engagement and decision-support for non-technical persons (Steenbeek et. al., 2020). The 2016 review of European Union (EU) MSP activities noted that initial assessment tools were either (i) not used as they did not fit the purpose of ‘real’ MSP planners or (ii) MSP planners did not know about them or (iii) their potential scope was not known. The review also found that tools were utilized more in the project context and less in the consultation process (European Commission, 2017).