inlandsea

An inland sea is a large body of seawater that is largely enclosed by land. These seas form in expansive basins where ocean water penetrates through limited openings, or where tectonic and sea-level processes create semi-enclosed water bodies. They are typically characterized by restricted exchange with the open ocean, variable salinity, and a strong influence from freshwater inflows, evaporation, and wind-driven circulation. Because of their semi-enclosed nature, inland seas can host marine-like ecosystems while accumulating nutrients and sediments from surrounding lands.

Notable examples include the Seto Inland Sea of Japan, which connects to the open ocean through straits and channels, the Caspian Sea, the largest enclosed body of water on Earth, and the Aral Sea in Central Asia, whose shrinking due to irrigation projects has produced major ecological and economic impacts. Other inland seas occur in various regions, reflecting local hydrological and geological context.

Hydrologically, inland seas often display wide salinity ranges from freshwater-like to highly saline, depending on river input, evaporation, and mixing with seawater. They support diverse fisheries and marine life but are sensitive to pollution, sedimentation, and climate-driven changes in precipitation and temperature. Their economic value typically centers on shipping, fisheries, tourism, and adjacent coastal activities.

Management of inland seas involves transboundary water governance, habitat conservation, and adaptation to changing water balances. Their enclosed nature makes them particularly vulnerable to human pressures such as water extraction, damming, pollution, and invasive species, which can alter salinity, productivity, and ecosystem resilience.