Snow height was measured by the Snow Buoy 2021S115, an autonomous platform, drifting on Antarctic sea ice, deployed during the RV Polarstern expedition PS124. The resulting time series describes the evolution of snow height as a function of place and time between 06 Mar 2021 and 18 Mar 2021 in sample intervals of 1 hour. The Snow Buoy consists of four independent sonar measurements representing the area (approx. 10 m**2) around the buoy. The buoy was installed on rafted first year ice. In addition to snow depth, geographic position (GPS), barometric pressure, air temperature, and an internal ice temperature were measured. Negative values of snow height occur if surface ablation continues into the sea ice. Thus, these measurements describe the position of the sea ice surface relative to the original snow-ice interface. Differences between single sensors indicate small-scale variability of the snow pack around the buoy. The data set has been processed and contains quality flags for different kinds for erroneous data. Flag values are the sum of individual error codes. The value of 0 refers to no error. Quality flag, position: The geographic position is flagged +1 if the drift velocity, as derived from the GPS longitude and latitude, exceeds a threshold of 10 deg latitude or 50 deg longitude per time step; +2 if the position exceeds extreme values, such as longitude > 360 deg; +4 if the position is exactly 0.0. Quality flag, snow: The snow height is flagged for each sensor +1 for manual corrections during processing (e.g. sensor issues); +2 if the snow accumulation exceeds 0.1 m per hour; +4 if the difference in snow height is larger than 0.03 m compared to values within the last and next 2 hours; +32 if the value exceeds the height of sensor on the platform at 1.5 m. Quality flag, temperature: The air temperature is flagged +1 for manual corrections during processing (e.g. sensor issues); + 32 if the value is below – 50 °C. Quality flag, pressure: The barometric pressure is flagged +1 for manual corrections during processing (e.g. sensor issues).