The occurrence, circulation, distribution, and properties of any liquid water residing beneath the surface of the earth. This article excludes any water molecules which constitute mineral species such as clays. Generally, ground water is that fraction of precipitation which infiltrates the land surface and subsequently moves, in response to various hydrodynamic forces, to reappear once again as seeps or in a more obvious fashion as springs. Most of ground-water discharge is not evident because it occurs through the bottoms of surface water bodies; in fact, large fresh-water springs are relatively common on the ocean bottom off the eastern coast of Florida.