Here we present measurements of hopanes from the mid-Cretaceous layer in drill core 9R and 10R at MARUM-MeBo70 Site PS104_20-2 (73.57°S, 107.09°W; 946 m water depth) for reconstructing past wildfire activity and vegetation near the South Pole. The site is located within the Pine Island cross-shelf trough in the Amundsen Sea Embayment (ASE), West Antarctica and was drilled during RV Polarstern Expedition PS104 in 2017. We applied the C31 hopane αβ 22S/(22S + 22R) ratio as a proxy to determine the thermal maturity of the organic matter25 and the C31 hopane ββ/(αβ + ββ) index as a peat-specific hopane-based pH proxy to reconstruct fossil pH conditions26.