Firn cores OH-7, OH-9 and OH-12 were retrieved from Plateau Laclavere, a small ice cap on the northernmost end of the Antarctic Peninsula. Firn core LP-01 was recovered from Plateau Louis Phillipe, which is located approximately 40 km south of Plateau Laclavere. OH-7 and OH-9 were drilled in January 2014 at an altitude of approximately 1130 m above sea level (a.s.l.) to a depth of 15.31 m and 11.65 m, respectively, using a mechanical 9 cm diameter drilling device (Rufli auger). OH-12 was drilled in January 2016 at about 1090 m a.s.l. to a depth of 19.93 m. LP-01 was also drilled in January 2016 at about 1390 m a.s.l. to a depth of 21.38 m. OH-12 and LP-01 were obtained using a portable solar-powered and electrically operated ice-core drill (Backpack Drill; icedrill.ch AG). Density measurements of the four firn cores were performed at the ice-core processing facilities of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven, Germany, in 2014/2015 (OH-9), 2016 (OH-7, OH-12) and 2018 (LP-01). X-ray microfocus computer tomography (ICE-CT; Freitag et al., 2013, DOI: 10.3189/2013JoG13J028) was used for the measurements, providing depth-density profiles with a resolution of better than 1 mm. The density data were used to analyse the firn core stratigraphy (e.g., determination of the snow-firn transition depth, identification of melt layers), to calculate diffusion lengths as well as to derive accumulation rates for the firn-core drill sites.