At present, ocean-going vessels mostly use heavy oil containing sulfur as fuel. The combustion of this fuel produces sulfur dioxide (SO2), which is harmful to health and the environment. At the beginning of 2020, the MARPOL Convention of the International Maritime Organization reduced the maximum permitted sulfur content in ship exhaust to 0.5% (m/m). For this reason, flue gas desulfurization plants are being retrofitted, in many cases using packed absorption columns with seawater as scrubbing liquid. In this work, the separation of SO2 in sea water with packed absorption columns is experimentally investigated at different water compositions (salinity and alkalinity) and operating conditions. For this purpose, mass transport measurements with columns of different diameters (DN150 and DN450) are carried out at two experimental stations. The measured data of this experimental investigation are compared with predictions of existing models for calculating the separation. From investigations with five different structured packings, it is found that with increasing salinity and alkalinity in the scrubbing liquid, SO2 removal is enhanced. It was found that doubling the alkalinity from 0 mmol/l to 2,5 mmol/l results in an increase in deposition of 27,1%; increasing the salinity from 0 g/kg to 33 g/kg results in an increase of 17,5%. An increase of the L/G ratio for any wash water composition leads to an improvement of the deposition. With the results of this work a contribution could be made to a better understanding of the absorption system SO2/seawater. In the future, this should lead to efficiency improvements in exhaust gas desulfurization on ocean-going vessels.