An in-depth explanation of the Earth's water cycle, including a hyperlinked diagram that provides direct access to information about each phase in the cycle.

The USGS gives an overview of the amount of water on Earth and where it is located. It gives a few interesting facts about the Earth's supply of water. Click Home to access the site in Spanish.

Find out how much of the water on Earth is actually usable by humans, and where the rest of it is located. Learn where our water comes from and why it never runs out. Click Home to access the site in Spanish.