About 70% of the Earth is covered with water, and 97% of that is part of the salty oceans. Only a small portion of the Earth's water is freshwater. This includes such things as rivers, lakes, and groundwater. Freshwater is needed for drinking, farming, and washing. There is even water in the form of ice at the poles. Without water, life as we know it would not exist.
Few rivers flow into the Pacific Ocean since it is bordered by mountains. However, many large rivers flow into the Atlantic Ocean, carrying sediment from the land. This process is one step of the water cycle.
(source:
http://www.windows.ucar.edu/tour/link=/earth/Water/overview.html)