If a permanent magnet is dropped into a deep body of fresh water such as Lake Superior, as it descends down, the rising water pressure should continually reduce the size of the magnetic field surrounding the magnet. This is because fresh water is diamagnetic and repels an external magnetic field.

So, the deeper the magnet descends, the more its magnetic field should be repelled by the ever-increasing pressure of the diamagnetic water molecules pushing against it.

Will rising water pressure around a permanent magnet reduce the size of its magnetic field