The Antarctic bed demonstrates complex behaviour comprising alternating warm- and cold-based areas. However, the distribution of warm- and cold-based areas, basal melting rates, and the structure
and age of the basal ice are not yet fully known. In the 2023–2024 season, we drilled an access borehole through 541m thick ice at Princess Elizabeth Land, 28 km south of the coast. Temperature
measurements at the bottom of the borehole revealed a cold underlying base despite a warm-based interface being predicted in advance as the most likely estimate. Our results imply that the Antarctic
base can be locally colder than currently assumed, and that thermal models, especially basal boundary conditions, should be carefully specified and provided with the confirmed input data.