A wealth of reports exist outlining impediments to access and use of biodiversity data in Europe. Broadly speaking, barriers fall into a handful of categories: resources, technical, legal, governance, and cultural. This first version of the document identifies the main barriers and focuses on the specific obstacles that are most challenging in enabling data to flow into the pathways developed within the DTO-BioFlow project, and highlights which types of data require the most effort when trying to onboard to the European Digital Twin of the Ocean (EU DTO). The main barriers highlighted in this report are derived from several European projects and studies related to marine biodiversity. The most significant barrier identified is the need for structured funding to ensure adequate resourcing of continuous data management through the marine biodiversity data life cycle. Coupled to this are issues in data sharing, understanding of the data and its context, and the adoption or use of standards. These barriers are validated by a survey of DTO-BioFlow partners, which relates the broader barriers to more targeted situations observed in the project's work packages and in their collective aim to mobilise different data pathways into the EU DTO. The DTO-BioFlow data flow blueprint (D3.1) is referenced, and areas where it has described practical methods that address the technical barriers for the DTO-BioFlow pathways are briefly highlighted. A second version of the document published at the end of the project (Autumn 2026) will work within this context to develop scenarios for the identified barriers that most directly impact marine biodiversity data pathways into the EU DTO. We will bring in use cases and examples developed within the other work packages. These will be designed to be widely applicable to the marine biodiversity data life cycle and used as a ‘playbook’ to demonstrate efforts in DTO-BioFlow to overcome such barriers and aid other initiatives in identifying pragmatic and technical solutions to barriers in dataflows.