Time series of temperature, salinity and pressure were recorded by instruments moored under drifting sea ice during the international Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) expedition. The instruments combined in this dataset were mounted on two different vertical lines suspended below the sea ice, horizontally separated by approximately 100 m, spanning similar time periods:• 4 RBR Concerto CTDs were moored at depths of 7 m, 49 m, 97 m, and 202 m on a 200 m long thermistor string (the thermistor string itself did not return any data). Attached to the same mooring was also a MicroRider measuring temperature microstructure; this dataset is published separately. This mooring was deployed on Leg 1 (15.12.2019) and recovered on Leg 3 (09.05.2020).• 3 Seabird SBE37 Microcat CTDs were mounted on the metal frames of the cluster mooring at nominal depths of 20, 50 and 100 m. This mooring was deployed during Leg 1 (07.12.2019) and recovered during Leg 4 (31.07.2020), but the instruments were operational only until 02.02.2020.The RBRs were set to a sampling interval of 15 sec, while the Microcats were set to an interval of 5 min. Further information about the moorings and their context can be obtained from the Overview of the MOSAiC expedition: Physical oceanography (Rabe et al. 2022).For quality control, we performed de-spiking of the data and bin-averaged to 1h time intervals. We then calibrated each instrument against the profiling CTD (ship- and ice-based, Tippenhauer et al. 2023): Temperature and salinity from each CTD cast during the deployment period were compared to the (1h- bin-averaged) data point of the moored instrument closest in depth and time. This produces a time series of differences for temperature and salinity. A linear fit was performed to these time series to determine offset and trend between the instruments. Both offset and trend were then applied to the quality controlled 1-h bin-averaged data of the moored instruments. In this dataset, we provide the quality controlled and calibrated data at 1h interval as well as raw data from the instruments together with essential meta-data.