… rare earth magnets are highly susceptible to corrosion regardless if the water is salty. They will corrode very quickly in fresh water - as any aquarium hobbyist coult tell you.

You aren’t claiming that magnets are impervious to corrosion, are you?

Neodymium magnets are typically coated with Nickel to prevent rust and corrosion from moisture, but unless coated with a special corrosion resistant coating, they are not waterproof. They should be kept away from water (especially salt water), as exposure to moisture can cause them to corrode and lose their magnetic strength over time. It is important to note that even a small amount of water, such as high humidity, can cause rust to form on the surface of the magnets. If you need to use neodymium magnets in a damp or wet environment, it is best to use a magnet with a corrosion resistant coating, or encase them in a waterproof container to protect them from moisture.