The Average Salinity of Sea Water is:
Answer: (1) 3.50%
The average salinity of sea water is 3.50%. The salinity of sea water is the vast majority of sea water. The density of seawater is 1020 to 1029 kg/m cube. Seawater contains 2.8 times more by carbonate then the seawater.
For more information click here Water Salinity Gradient