Equivalent black carbon (eBC) mass concentration was measured with a commercial aethalometer (model AE33, Magee Scientific, Berkeley, USA). Measurements were performed onboard of the Swedish icebreaker (I/B) Oden from August to September 2018 as part of the expedition Arctic Ocean 2018. Black carbon is an anthropogenic aerosol resulting from incomplete combustion (e.g. traffic or ship exhaust or industrial emissions). It is relevant for various atmospheric processes such as its influence on radiative transfer within the Earth's atmosphere. The instrument was located on the 4th deck of I/B Oden, switching hourly between a total and interstitial air inlet, with cutoff sizes of 40 and 1 µm respectively. Optical absorption was measured at 7 different wavelengths simultaneously, with a 1 second time resolution. We used the absorption at 880 nm (channel 6) to derive eBC, using a mass absorption cross-section value of 7.77 m² g ⁻¹.