A halocline (or salinity chemocline), from the Greek words hals (salt) and klinein (to slope), refers to a layer within a body of water (water column) where there is a sharp change in salinity (salt concentration) with depth.
Haloclines are typically found in oceans or large estuaries and it is a type of chemical stratification that is most commonly found in places where freshwater from rivers or melting ice, mixes with salty ocean water.