This paper reports a case study examining the effects on the shipboard work environment of an operative decision to change fuel oil type on two Swedish passenger vessels operating in the Baltic Sea. The results show positive changes in work tasks, reduced exposure to harmful pollutants evaporating from the fuel, reduced use of chemicals for cleaning, and a generally cleaner work environment. The outcome illustrates the benefit of a systems perspective when evaluating environmental interventions. Here, the intervention can be seen as an investment that not only reduces emissions to the environment, but contributes towards sustainable working life at sea.