The whole Earth geohydrologic cycle describes the occurrence and movement of water from the clouds to the core. Reservoirs that comprise the conventional hydrologic cycle define the exosphere, whereas those reservoirs that are part of the solid Earth represent the geosphere. Exosphere reservoirs thus include the atmosphere, the oceans, surface water, glaciers and polar ice, the biosphere, and groundwater. Continental crust, oceanic crust, upper mantle, transition zone, lower mantle and the core make up the geosphere. The exosphere and geosphere are linked through the active plate tectonic processes of subduction and volcanism. While the storage capacities of reservoirs in the geosphere have been reasonably well constrained by experimental and observational studies, much uncertainty exists concerning the actual amount of water held in the geosphere. Assuming that the amount of water in the upper mantle, transition zone, and lower mantle represents only 10%, 10%, and 50% of their storage capacities, respectively, the total amount of water in the Earth's mantle (1.2 × 10 21 kg) is comparable to the amount of water held in the world's oceans (1.37 × 10 21 kg). Fluxes between reservoirs in the geohydrologic cycle vary by ~7 orders of magnitude, and range from 4.25 × 10 17 kg/yr between the oceans and atmosphere, to 5 × 10 10 kg/yr between the lower mantle and transition zone. Residence times for water in the various reservoirs of the geohydrologic cycle also show wide variation, and range from 2.6 × 10 -2 yr (~10 days) for water in the atmosphere, to 6.6 × 10 9 yr for water in the transition zone.