Seawater is the water found in oceans and seas, covering about 71% of the Earth's surface. It is primarily composed of water (about 96.5%) and contains various dissolved salts, with sodium chloride being the most abundant. The average salinity of seawater is around 3.5%, meaning that every liter of seawater contains about 35 grams of dissolved salts.
Seawater plays a crucial role in regulating the Earth's climate and supporting marine ecosystems. It is home to a diverse range of organisms, from tiny plankton to large whales. Additionally, seawater is essential for human activities such as fishing, transportation, and recreation.