Carine Renewable Energy (MRE) is making use of many phenomena in the ocean, such as waves, tides, currents, and thermal or salinity gradients, to supply stable and reliable power for the transition to a low-carbon world. Review of various sources for generating electricity and the current situation of important MRE types. Since no single MRE technology can achieve the best efficiency on its own, integrated multi-energy systems are being developed more and more frequently. The basic ideas and cooperative advantages of the above systems are introduced to strengthen integration capacity, increase the stability of power output, and improve resource utilisation efficiency. In addition, we have identified several reasons why integrated MREs have not been widely deployed, such as the complexity of system design, difficulties in coupled modelling, a lack of experimental verification, problems with operational reliability, and barriers to grid connection. Finally, we will present some ideas for developing integrated MRE systems in deep-sea exploration, industrial convergence, and the transition to a sustainable energy future.