During the MOSAiC expedition, the German research icebreaker Polarstern spends a full year drifting through the Arctic Ocean. Scientists from 20 countries participate in the largest polar expedition in history exploring the Arctic climate system. The experiment covers a large suite of in-situ and remote sensing observations of physical, ecological and biogeochemical parameters to describe the processes coupling the atmosphere, sea ice, and ocean. In addition to forefront instrumentation and observational techniques, proper data management is essential for large and complex projects and field programs. Key elements are agreements on consistent sampling strategies, the possibility to monitor the data flow, to facilitate near real-time processing, and analysis and sharing of data during and long after the expedition. Furthermore, data publication and documentation are crucial for such a collaborative effort and will build the legacy of the project and finally take climate science to the next level. We adapted our modular research data management framework O2A “Data flow from Observations to Archives” to meet the expedition requirements and ensure central data archival for generations to come. Researchers register all necessary sensor metadata beforehand. Essential metadata of scientific actions in the field are ingested immediately with the FloeNavi, a novel system enabling navigation on a drifting ice floe. O2A provides tools to automatize data ingestion, monitor the data flow and process, analyze and publish data. Integration of ship- and land-based components and a shared storage ensure seamless continuation of collaboration during and after the expedition laying the fundamentals for numerous data publications.