A static fluid is one that is at rest. In a static fluid:

1. Pressure increases with depth.
2. Two points at the same vertical position experience the same pressure, no matter what the shape of the container.

If point 2 is a vertical distance h below point 1, and the pressure at point 1 is P₁, the pressure at point 2 is:

P₂ = P₁ + ρgh

Point 2 does not have to be directly below point 1 - all that matters is the vertical distance. Any horizontal displacement is irrelevant.

Click and drag the sensors to measure pressure. The red sensor measures correctly only in air; the purple one measures correctly only in the water.