This Factsheet presents a summary of the DTO-BioFlow Blueprint (Deliverable D3.1), developed within the framework of the DTO-BioFlow project funded by the EU Horizon Europe programme. The Blueprint outlines the technical and conceptual foundation for integrating diverse marine biodiversity data into the European Union’s Digital Twin Ocean (EU DTO), with a particular focus on establishing sustainable and standardized data flows. Marine biodiversity data—ranging from genomics and plankton imaging to biologging and passive acoustic monitoring—are currently fragmented, with many datasets not reaching long-term repositories due to technical, procedural, or interoperability challenges. The Blueprint defines the architecture, processes, and partnerships needed to overcome these barriers and channel high-quality, FAIR (Findable, Accessible, Interoperable, Reusable) data into EMODnet Biology and the EU DTO infrastructure. The data flow model introduced in the Blueprint captures how raw observational data, collected by various actors using diverse technologies, is processed, quality-checked, standardized, and routed through integrators and repositories toward final integration into EMODnet Biology. From there, data is harvested into the EU DTO Data Lake to support ecosystem modelling, scenario simulations, and policy-relevant applications. By providing a harmonized framework for new data types and establishing clear pathways for data ingestion, the DTO-BioFlow Blueprint serves as a critical stepping stone for enriching the biological component of the EU Digital Twin Ocean.