Hydrosphere (Greekhydro- means "water")
in physical geography, describes collective mass of water that is found under, on and over the surface of the Earth.
Water comprising hydrosphere is found in various forms :
... Powell, (1834-1902), explorer, environmentalist
Nathaniel Pryor[?], (c 1785-1850), US explorer
Pytheas, (died 1984), Greek explorer who visited Britain and othe ...