Fall 2019 H2O on the GO Water (H2O) is essential for all life and is always moving on, above and below the earth's surface. This movement of water between earth's land, atmosphere and oceans is called the water cycle. Let's look at each part of the water cycle for a better understanding of what it is and how water moves through it. As you look at the water cycle, think about how each part combines to create the entire cycle.