See http://www.lerc.nasa.gov/WWW/K-12/Wi..._pressure.html

The Pressure of a fluid is determined by density and depth, the volume has nothing to do with it.

This is because a fluid exerts pressure equally in all directions.

Or are you going to make be dig up my Fluid Mechanics notes to find the derivation for the formula : P = Pa + roe*g*h (notice the absence of any dimension other than height)

I believe you may be confusing force and pressure.