The growing trend of the cruise ship industry, together with increasing concerns over its impact on the environment, makes these ships a much relevant target for efforts toward increasing ship energy efficiency, thus ultimately reducing fuel consumption and emissions of carbon dioxide and other air pollutants. In this work, we propose the application of process integration methods to the case of a cruise ship operated in the Baltic Sea. Given the basic energy demand of the ship and its expected operational profile, we optimize the design and operations of its power plant. The results of the application of process integration show that, for the specific case of interest: - A larger number of engines (8), subdivided in two different sizes, allows reducing fuel consumption by up to 3% when compared to a smaller number (4) of equally sized engines.  The application of pinch analysis allows identifying potential for heat integration within the system, and particularly shows how the exhaust gases provide a particularly significant potential for improved use on board. - The installation of a waste heat recovery system allows to achieve savings of up to 4.8% for a steam-based Rankine cycle and of up to 6.9% for an organic Rankine cycle based on ethanol as a working fluid - Using batteries for engine load levelling as a potential of up to 1.6% fuel savings.