A halocline is a layer in a body of water where there is a rapid change in salinity with depth. This phenomenon typically occurs in oceans, seas, and large lakes, where the upper layer of water has a different salt concentration than the deeper layers. The halocline can affect the distribution of marine life and influence water circulation patterns. Haloclines are often found in conjunction with other layers, such as thermoclines, which are characterized by changes in temperature. Together, these layers create distinct environments that can impact ecosystems and the behavior of organisms like fish and plankton.