This dataset consists of glacial and Mid-Holocene multi-species benthic δ18O mean data from cores that form depth transects at Cape Hatteras and Blake Outer Ridge. The mean δ18O for each core was derived by averaging multiple monospecific measurements from different depth intervals corresponding to the MH or LGM. The standard error is σ/√n; where σ is the multi-species replicate error at either CH or BOR across both time periods, and n is the number of species analysed at each core. Stable isotope measurements were performed using a VG Isogas SIRA mass spectrometer with Multicarb preparation system (>80 μg) and a Thermo MAT253 isotope ratio mass spectrometer with Kiel IV carbonate preparation device (80 μg) or with a Thermo MAT253 isotope ratio mass spectrometer with Kiel IV carbonate preparation device (<80 μg).