A magnet system for removable attachment of a bag to a water board preferably includes at least one magnet and at least metal disc. The at least one magnet is retained in or on a bottom of a bag. The at least one metal disc must fabricated of a ferrous material, such as steel. The at least one metal disc is coated with a water impermeable substance to prevent rusting. The at least one metal disc is retained on a surface of the water board. The bag will be removably retained relative to the water board, when a magnetic field of the at least one magnet is in contact with the at least one metal disc.