Marine microbiology is a branch of microbiology that deals with the study of microorganisms inhabiting marine environments, including oceans, seas, coastal waters, estuaries, mangroves, coral reefs, deep-sea sediments, and hydrothermal vents. It focuses on the diversity, distribution, physiology, ecology, and economic importance of marine microorganisms and their roles in maintaining marine ecosystem functions.

Marine microbiology is an important branch of microbiology that explores the diversity, activities, and applications of microorganisms in marine environments. These microorganisms sustain marine food webs, recycle essential nutrients, influence global biogeochemical cycles, contribute to climate regulation, and provide valuable resources for biotechnology, medicine, and environmental management. The study of marine microbiology is therefore essential for understanding ocean health, conserving marine biodiversity, and developing sustainable technologies.