Seas

A sea is a large body of saltwater smaller than an ocean, usually partly enclosed by land and connected to the world ocean. Seas vary widely in size, depth, and geography, and their boundaries are often defined by coastlines and cultural usage as much as by strict physical criteria.

Many seas are marginal or semi-enclosed, influenced by river outflows, wind, tides, and ocean currents. They tend to be shallower and more productive than open oceans, though exceptions exist. Examples include the Mediterranean Sea, the Baltic Sea, and the Black Sea. The Caspian Sea is commonly called a sea but is technically a landlocked lake.

Ecology and economy: Seas support diverse marine communities and provide seafood, minerals, and energy resources. They are major corridors for international shipping and tourism, and host coastal industries such as fishing, aquaculture, and offshore energy development.

Environmental pressures: Seas face pollution, nutrient enrichment leading to eutrophication, overfishing, habitat destruction, invasive species, and the impacts of climate change, including warming, acidification, and sea-level changes. Protection and management rely on international law, regional agreements, and national policies, including environmental impact assessments and marine protected areas.

Overall, seas are integral parts of the global ocean system, linking continents through trade, climate, and biodiversity while requiring careful stewardship to sustain their ecological and economic value.