Hydrostatic pressure and air pressure

With this experiment you can prove the hydrostatic pressure growing with immersion depth.
A ballon is being attached to a long glass tube. Then a balloon is filled with colored fluid and being put in a tank that is filled with water. (see picture below)

The deeper the balloon is dipped into the water, the more it is being compressed and the more compressed it is the higher the water rises in the glass tube. So with immersion depth pressure rises.
Retracting the balloon from the water reverses the process.

The picture shows that the balloon is being compressed heavily once he is under water.

This priciple is being used by pressureinstruments.