marine

Marine refers to anything related to the sea or ocean. The term comes from the Latin mare, meaning sea, and is used across science, policy, and everyday language. In biology and ecology, marine denotes organisms and ecosystems that live in or interact with saltwater environments, including open oceans (pelagic zone), the seabed (benthic), coastal areas, coral reefs, kelp forests, and seagrass beds. Marine life ranges from microscopic plankton to large mammals such as whales. Marine biology studies physiology, behavior, and ecological relationships in saltwater habitats, while physical oceanography investigates waves, currents, temperature, salinity, and chemical properties affecting marine life.

Human activity is closely linked to the sea, including fisheries, shipping, energy extraction, and tourism. The term marine also appears in the names of institutions and armed forces, notably the marine corps, which originated as shipborne infantry. In policy and law, the United Nations Convention on the Law of the Sea (UNCLOS) regulates rights and responsibilities over marine areas, including territorial waters and exclusive economic zones.

Conservation concerns center on biodiversity loss, overfishing, pollution, habitat destruction, and climate-driven changes such as warming and ocean acidification. Responses include marine protected areas, sustainable fisheries management, pollution control, and international cooperation. Understanding marine systems is essential for predicting climate impacts, supporting coastal communities, and maintaining the resources and services provided by oceans.