Abstract: This database presents a compilation of historical oceanographic observations from across the South Atlantic, focusing on the West African Margin. The dataset combines discrete bottle and sensor data from 74 years (1950 to 2024) of research cruises and autonomous platform deployments, integrating repositories (PANGEA, GEOTRACES, BCO-DMO, MIMS) with regional datasets (the bulk of which was compiled in Carlson et al., 2025) and data extracted from peer reviewed journal articles. This compilation is designed to support research into physical and biogeochemical ocean processes by providing a unified, harmonized dataset for use in modelling and climate studies. Data sources: This dataset is a compilation of previously published data including: · Global repositories: GEOTRACES intermediate product (IDP2025: https://doi.org/10.5285/42c92148-8d03-8be6-e063-7086abc09f0c), PANGEA (https://doi.org/10.1038/s41597-023-02269-x), and BCO-DMO (https://doi.org/10.17616/R37P4C). · National repositories: Marine Information Management System (MIMS) (https://doi.org/10.17616/R31NJNH3)used to access data from regional programs such as the Integrated Ecosystem Programme (IEP), South African Mooring Bouy Array (SAMBA), and the St Helena Bay Monitoring Line (SHBML) datasets. · Literature synthesis: data extracted from published peer reviewed studies; citations can be found in the database. Parameters: · Spatial and temporal data: Latitude, Longitude, Depth (m), date, and time. · Physical parameters: Temperature (oC), Practical Salinity (PSS−78), and Dissolved Oxygen (μmol/kg). Quality control: Dissolved oxygen data were quality controlled following the procedures described in Gouretski et al. (2024), Each check was applied sequentially: 1. Geographical location (bottom-depth) check: Compare the deepest sample of each profile to the local GEBCO bathymetry (GEBCO Bathymetric Compilation Group, 2025). Profiles with sampling depths exceeding the local seafloor depth were flagged. 2. Global oxygen range check: Oxygen levels outside depth-varying limits, defined at the 0.05 normalized frequency threshold of the global bottle data archive histogram, were flagged as gross errors. 3. Oxygen and temperature consistency check: Where temperature measurements are available, identify and remove values that fall outside the expected O2 limits for a given temperature (evaluated in 1 °C bins), which helps detect unit or sign errors. 4. Maximum oxygen solubility check: Where temperature and salinity measurements are available, observed oxygen concentrations were compared against the theoretical saturation limit. Values exceeding the physical solubility bound were flagged. 5. Stuck value check: Profiles exhibiting near-constant oxygen values with depth (very low vertical standard deviation) were identified as likely sensor malfunctions and flagged. Dataset limitations: While every effort has been made to compile all available reliable data, some studies may not have been included. Additionally, large data gaps exist in the spatial and temporal coverage of the data. Citation: It is strongly encouraged to cite the original data listed in the references column of the database, in addition to citing this compilation. This ensures credit is given to the researchers who conducted the original studies. References: Biological and Chemical Oceanography Data Management Office. (2026). Biological, chemical, physical, biogeochemical, ecological, environmental and other data collected from around the world during historical and contemporary periods of biological and chemical oceanographic exploration and research managed and submitted by the Biological and Chemical Oceanography Data Management Office (BCO-DMO). NOAA National Centers for Environmental Information. https://doi.org/https://doi.org/10.17616/R37P4C Carlson, A. J., Siedlecki, S. A., Granger, J., Veitch, J., Pitcher, G. C., Fearon, G., Soares, F., Zhou, M., Flynn, R. F., & Fawcett, S. E. (2025). Seasonal Source Water Changes and Winds Contribute to the Development of Hypoxia in St Helena Bay Within the Southern Benguela Upwelling System. Journal of Geophysical Research: Oceans, 130(4), e2024JC021702. https://doi.org/10.1029/2024JC021702 Felden, J., Möller, L., Schindler, U., Huber, R., Schumacher, S., Koppe, R., Diepenbroek, M., & Glöckner, F. O. (2023). PANGAEA - Data Publisher for Earth & Environmental Science. Scientific Data, 10(1), 347. https://doi.org/10.1038/s41597-023-02269-x GEBCO Bathymetric Compilation Group. (2025). The GEBCO_2025 Grid - a continuous terrain model for oceans and land at 15 arc-second intervals. NERC EDS British Oceanographic Data Centre NOC. https://doi.org/10.5285/37c52e96-24ea-67ce-e063-7086abc05f29 GEOTRACES Intermediate Data Product Group. (2025). The GEOTRACES Intermediate Data Product 2025 (IDP2025). NERC EDS British Oceanographic Data Centre NOC. https://doi.org/10.5285/42c92148-8d03-8be6-e063-7086abc09f0c Gouretski, V., Cheng, L., Du, J., Xing, X., Chai, F., & Tan, Z. (2024). A consistent ocean oxygen profile dataset with new quality control and bias assessment. Earth System Science Data, 16(12), 5503–5530. https://doi.org/10.5194/essd-16-5503-2024 Marine Information Management System (MIMS). (2026). re3data.org - Registry of Research Data Repositories. https://doi.org/https://doi.org/10.17616/R31NJNH3