Technologies to harvest marine renewable energies (MREs) are at a pre-commercial stage, and significant R&D progress is still required in order to improve their competitiveness. Therefore, hybridization presents a significant potential, as it fosters synergies among the different harvesting technologies and resources. In the scope of this Special Issue, hybridization is understood in three different manners: (i) combination of technologies to harvest different MREs (e.g., wave energy converters combined with wind turbines)
(ii) combination of different working principles to harvest the same resource (e.g., oscillating water column with an overtopping device to harvest wave energy)
or (iii) integration of harvesting technologies in multifunctional platforms and structures (e.g., integration of wave energy converters in breakwaters). This Special Issue presents cutting-edge research on the development and testing of hybrid technologies for harvesting MREs and intends to inform interested readers on the most recent advances in this key topic.