Many marine species, from large organisms to microorganisms, are found in the seas and oceans. The latter comprises fungi, bacteria, and archaea, which can survive in extreme environments through physiological and biochemical mechanisms. Little is known about the function of the marine microorganisms in these environments; however, their potential as a source of bioactive compounds such as terpenes, alkaloids, polyketides, anthraquinones, fatty acids, and polysaccharides, among others, has been explored. Obtaining these bioactive compounds for possible use in different industries has required biotechnological processes such as fermentation. Likewise, these compounds have demonstrated antimicrobial, antidiabetic, anti-inflammatory, and anticancer activity, among others. These properties make marine microorganisms an interesting and relevant source of bioactive compounds with great potential for use in health and other industries as ingredients.