👉 Seawater is a type of freshwater that originates from the oceans. It is made up primarily of salt, which can range in concentration from 3 to 5 parts per million (ppm). Seawater has a high degree of salinity and is typically cloudy or greenish-white in color due to the presence of dissolved salts. The term "seawater" refers to this type of freshwater that originates from the oceans.