Liquid water

right|thumb|upright=1.5|An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the [[water table (4), and three different wells (7, 8 and 9) dug to reach it.]]

Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentrati

water with salinity between freshwater and saline water

water that contains a significant concentration of dissolved salts

water that has a high mineral content

water treated to remove dissolved solutes or suspended impurities

pollution that occurs when when pollutants are released to the ground and seep down into groundwater

stagnation of water

process of infiltration and percolation of water in the ground and aquifers

foam created by the agitation of seawater

Polywater was a hypothesized polymerized form of water that was the subject of much scientific controversy during the late 1960s, first described by Soviet scientist Nikolai Fedyakin. By 1969 the popular press had taken notice of Western attempts to recreate the substance and sparked fears of a "polywater gap" between the United States and Soviet Union. Increased press attention also brought with it increased scientific attention, and as early as 1970 doubts about its authenticity were being circulated. By 1973 it was found to be illusory, being just water with any number of common compounds c

mass fraction in a saturated mixture that is vapor

water purified to uncommonly stringent specifications

untreated water found in a natural environment

mixture of dissolved mineral salts (and sometimes vitamins) that simulates seawater

thumb|Mineral stains, Rosedale, North Yorkshire|Rosedale Cliffs – marks caused by chalybeate waters thumb|Chalybeate spring below Cascada de los Colores, La Palma