This paper presents a case study comparing sea and road transport modes for a Norwegian producer of plastic pipes for the construction industry. The study is based on three cases in which CO2e emissions and transport costs were calculated and compared. The main research problem was to analyze whether sea transport is more environmentally friendly than road transport in terms of emissions of greenhouse gases (GHG) and cost-effectiveness. The results from the three analyzed cases show that sea transport is not always the most environmentally friendly and cost-effective mode. We suggest that in order to evaluate the environmental impact and cost-effectiveness of sea transport as an alternative to road transport, such factors as transport distances, load weight/volume ratios, ship load factors, number of port calls, ship sizes, and ship fuel types for each specific case need to be analyzed.