Water and gravity: look at this video

[kajunbee]

https://youtu.be/tvSo7CXQQ7c

[kolbacict]

Pressure in a sealed vessel is equal throughout the vessel
One cannot sink while the other rises

Can you make a diver so that when the water pressure rises, he floats instead of sinking?

[sm0ky2]

To invert the scenario, implies an inversion of the compression.


Such a bobber would use vacuum-based displacement,
where-in external pressure activates a secondary internal actuator
Increasing the physical volume of the air chamber,


In this bobber the flexible material would be replaced by an expanding rigid chamber
that could support lower internal pressure.
(vacuum-spring?)
The force required to do this would be substantially large.
It may be mechanically possible, but wouldn't make sense to build such a thing for this purpose

[sm0ky2]

In air buoyancy would be more suitable for vacuum-based buoyant devices

[kolbacict]

The force required to do this would be substantially large.
It may be mechanically possible, but wouldn't make sense to build such a thing for this purpose

In that case we could to use single aquarium without   partitions.
And the water level would not change from above.