Would anybody know how much the ocean would expand providing the atmospheric pressure was reduced?

Question

I know the atmospheric pressure is 14 pounds per square inch. How much expansion would there be if there is less atmospheric pressure? Per pound would be fine if feasible..

Answer 1

Liquids are essentially non-compressible. If adding pressure will not reduce the volume, reducing pressure will not cause it to expand. (There is a SMALL change but it is hardly significant.)
There are gasses dissolved in water and they would want to leave, and if you lower the pressure far enough, the water would boil off.
Reducing pressure lowers the boiling point.