Marine energy technologies harness the renewable power of sea waves and tides to generate clean electricity. This paper reviews tidal, wave, solar, and wind energy technologies, compares their economics and sustainability, and examines the prospects and challenges of marine energy in Saudi Arabia. With immense coastlines along the Red Sea and Persian Gulf, Saudi Arabia has abundant tidal and wave energy potential. However, realization of this potential faces challenges including high infrastructure costs, impacts on marine ecosystems, and the need for supportive policies and grid integration. With strategic government support for technology innovation, infrastructure development, and policy incentives, Saudi Arabia can utilize its marine energy resources to diversify its energy mix and progress towards its renewable energy goals.