A thermocline is a distinct layer in a body of water where the temperature changes rapidly with depth. Typically found in oceans and large lakes, it separates the warmer, mixed water at the surface from the colder, deeper water. This temperature gradient can significantly affect marine life and water circulation. The presence of a thermocline can influence various ecological processes, such as nutrient distribution and oxygen levels. In oceanography, understanding thermoclines is essential for studying marine ecosystems and predicting how climate change may impact aquatic environments.