Salinity> Salinity is the amount salt found in one kilogram of water, ( there are 1,000 grams in a kilogram). The average Salinity is 35 parts per thousand (ppt). Usually it varies between 32-37 ppt. Rainfall, evaporation, river run-off and ice formation cause the vary. An example would be a ocean with a river run-off it's average would be 16 ppt. Fresh water Salinity is usually less than 0.5. Water between 0.5n and 17 ppt is called brackish.
 

A little fact about pressure Though we don't feel it 14.7 pounds per square inch (psi) are pushing down on our bodies when we are at sea level.