This dataset contains point estimates of meteoric water and sea ice meltwater fraction in the ocean polar watermasses, as well as the global stable oxygen isotopic composition (d18O) of meteoric water. These estimates were inferred from co-located d18O, salinity and temperature observations from NASA-GISS (Schmidtet al., 1999) and CISE-LOCEAN (Reverdin et al., 2022) datasets, as well as individual cruise data available at the British Oceanographic Data Centre (https://www.bodc.ac.uk/), through the Self Organizing Map machine learning approach to identify distinct salinity-d18O relationships in water masses. More information can be found in the associated manuscript Davila et al. (2025). Please cite as: Davila et al., Freshwater Sources in the Global Ocean through Salinity-d18O Relationships: A Machine Learning Solution to a Water Mass Problem; JGR:Oceans (2025), DOI: 10.1029/2024JC022122