Snow and first-year sea ice ridge thickness, draft, and morphology were measured using a 2-inch ice drilling auger (Kovacs Enterprises) during walking surveys on the first-year ice ridge during the MOSAiC expedition. Drilling was performed during January, February, and July 2020 across three drilling transects located 50 m from each other. The total covered area was approximately 100 m by 35 m. The investigated “Alli's Ridge” was formed on 7-9.01.2020 between second-year ice, 0.9-1.0 m thick first-year ice, and lead ice mainly from lead ice of 0.2-0.4 m thick blocks. The ridge was located on drifting sea ice in the Arctic Ocean within the Central Observatory of MOSAiC.The table contains the event label (1), event ID (2), time (3) and global coordinates (4,5) of each drilling measurement. Each separate drilling hole has its number (6), and local coordinates X (7) and Y (8) in [m], given relatively to the point with the highest freeboard with (0,0) local coordinates. Global coordinates are given for the local coordinates of (7.5,0). For each drill hole, the depth relative to the waterline of the top (9) and bottom (10) interface of each separate layer is given together with its ice type (11). Ice types include very snow, very soft ice, softer ice, soft ice, ice, hard ice, and water. Drill hole with local coordinates of (7.5,0) coincides with the ice mass balance buoy SIMBA 2020T61 installation described in doi:10.1594/PANGAEA.926580. Drill hole with local coordinates of (2.5,10) coincides with the salinity/isotope ice core described in doi:10.1594/PANGAEA.943746.Drilling_map.jpg is giving an image with an overview of all drill holes and their location in the local coordinate system with a contour plot of the keel depth equal to the maximum ice draft.

These measurements were performed as part of the project Ridges - Safe HAVens for ice-associated Flora and Fauna in a Seasonally ice-covered Arctic OCean (HAVOC), funded by the Research Council of Norway, project number: 280292.