During RV Meteor cruise M188 in the eastern South Atlantic (7 March - 13 April, 2023) conductivity, temperature, and depth (CTD) measurements were made using a Sea-Bird 9plus instrument. Calibration for conductivity was performed at sea using water samples. The CTD data were processed using the standard Seabird algorithms. Downcast data were separated and averaged over 1 dbar intervals. The accuracy of the calibrated CTD measurements is: 1 dbar for pressure, 0.002 °C for temperature, 0.003 psu for salinity.