Ocean currents are strongly controlled by seafloor topography. Recent studies have shown that small-scale features with slopes steeper than 0.05° significantly affect subsurface eddy velocities and the vertical structure of ocean circulation patterns. Such slope gradients represent the majority of the present-day oceanic basins. Modeling past oceanographic conditions for key climate stages requires similarly detailed paleo seafloor topography grids, in order to capture ocean currents accurately, especially for ocean models with sufficient resolution (<0.1°) to resolve eddies. However, existing paleobathymetry reconstructions use either a forward modeling approach, resulting in global grids lacking detailed seafloor roughness, or a backward modeling technique based on sediment backstripping, capturing realistic slope gradients, but for a spatially restricted area. Both approaches produce insufficient boundary conditions for high-resolution global paleo models. Here, we compute high-resolution global paleobathymetry grids, with detailed focus on the Southern Ocean, for key Cretaceous and early Cenozoic climate stages. We backstrip sediments from the modern global bathymetry, allowing the preservation of present-day seafloor slope gradients. Sediment isopach data are compiled from existing seismo-stratigraphic interpretations along the Southern Ocean margins, and expanded globally using total sediment thickness information and constant sedimentation rates. We also consider the effect of mantle flow on long-wavelength topography. The resulting grids contain realistic seafloor slope gradients and continental slopes across the continent-ocean transition zones that are similar to present-day observations. Using these detailed paleobathymetry grids for high-resolution global paleo models will help to accurately reconstruct oceanographic conditions of key climate stages and their interaction with the evolving seafloor.

This dataset provides a harmonised, inter-calibrated collection of multi-platform oceanographic observations acquired during the FOCUS/SWOT-ACC voyage (IN2023_V07) in the Southern Ocean during 2023–2024. Observations were collected in the vicinity of the Antarctic Circumpolar Current Polar Front and its standing meander downstream of the Southeast Indian Ridge using multiple observing platforms, including ship-based CTD casts, Triaxus surveys, autonomous gliders, EM-APEX profiling floats and BGC-Argo floats. The source datasets had previously undergone platform-specific processing and initial quality control by the relevant data providers. An additional cross-platform consistency assessment and inter-calibration was subsequently undertaken to improve comparability among the observing systems. Temperature, salinity and dissolved oxygen were evaluated using overlapping or closely matched observations, with systematic offsets assessed relative to instrument accuracy, the variability of the observed differences, and the persistence of offset sign. Corrections were applied where the observed differences were considered sufficiently systematic and robust. The resulting data product contains the processed and inter-calibrated observations in NetCDF format and is intended to provide a consistent, analysis-ready dataset for multi-platform studies of hydrographic structure, water-mass variability and frontal processes in the Polar Front region. The original source datasets remain available through their respective institutional and community repositories. Documentation accompanying this dataset describes the source data, inter-calibration methodology, applied corrections, data provenance and relevant limitations.