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.
Waterproof/Corrosion Resistant Coatings
If you are looking for waterproof neodymium magnets, we have a few options.
Sewing Magnets - These magnets are encased in a waterproof PVC pouch that protects them from moisture. The PVC pouch also enables the magnets to be sewn into fabric or other materials.
Black Epoxy Coated Magnets - The black epoxy coating on these magnets provides much greater corrosion resistance than normal Nickel coatings.
Plastic Coated Magnets - These magnets are coated with a 1mm thick layer of ABS plastic. The plastic both protects the magnet from moisture and prevents damage to the magnet itself.