Seawater is water from a sea or ocean with salinity of approximately 3.5%, or 35 parts per thousand and has the elemental composition of, 85.84% oxygen, 10.82% hydrogen, 1.94% chlorine and 1.08 sodium.
Seawater, or salt water, is water from a sea or ocean. Seawater elemental composition
(salinity = 3.5%) Oxygen 85.84 10.82 Hydrogen 1.94 Chlorine 1.08 Sodium On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/l, 599 mM). 
