A thermocline is a distinct layer in a body of water, such as an ocean or lake, where the temperature changes rapidly with depth. Above this layer, the water is warmer and less dense, while below it, the water is colder and denser. This temperature gradient can significantly affect marine life and water circulation. Thermoclines are most commonly found in large bodies of water during warmer months. They can influence various ecological processes, including photosynthesis and nutrient distribution. Understanding thermoclines is essential for activities like fishing and diving, as they impact where certain species are located.