The Nordic Spatial project has created the NordicSpatial mapping tool – a free, web-based map tool for data sharing and cross-border collaboration. The aim of the project was to facilitate a holistic approach to cross-border marine spatial planning in the Nordic and Baltic states and create a shared understanding of the marine environment across national boundaries. The mapping tool allows users to combine and visualize marine data from different national and regional sources, and supports a common knowledge base for sustainable and coordinated management of marine resources in the Nordic and Baltic regions. The NordicSpatial tool is currently a demonstrator tool, demonstrating functionality in real scenarios with authoritative data. With further development, it could become a fully operational tool for coordinated marine spatial management across borders.