SHOM (Service hydrographique et océanographique de la Marine) contributed to the early-stage site knowledge base for the Bretagne Nord Ouest floating offshore wind zone by producing several 2025 “Synthèse état de connaissance initiale” studies made available on the project’s official studies page. These syntheses form part of the baseline technical characterisation used to inform the State-led planning and competitive tender process for AO10 in Northwest Brittany. For metocean-related conditions, SHOM was cited as the author of dedicated syntheses covering tides (“Marée 2025”), currents (“Courants 2025”), and swell (“Houle 2025”). These documents support understanding of the marine climate and hydrodynamic regime relevant to floating wind development, including the assessment of environmental and operational constraints. For seabed and site survey baselines, SHOM was also credited with hydrographic/geophysical syntheses including bathymetry (“Bathymétrie 2025”), anthropic elements (“Éléments anthropiques 2025”), and hydrology (“Hydrologie 2025”), as well as a ground-condition related synthesis on sedimentology (“Sédimentologie 2025”). Together, these studies contribute to the initial appraisal of seabed characteristics and existing features within the project study and consultation area.