The 2025 Multi-sensor Ocean Colour course (MSOC), is a 5-day, face-to-face, advanced training event hosted at EUMETSAT, following the December IOCS conference. This collaborative EUMETSAT/NASA/ESA activity, support by the IOCCG and Copernicus, will cover a range of topics that are central working with ocean colour data from spac. This will include data access, atmospheric correction, algorithm selection, multi-sensor interoperability and validation. It will focus on single sensor (Copernicus Sentinel-3 OLCI, Copernicus Sentinel-2 MSI, NASA PACE OCI) and multi-sensor workflows and synergy. All course materials will be made available for a broader audience, once the event is complete.