Sea mineral concentrates are generally legitimate, often sourced from the Great Salt Lake or deep ocean water to provide concentrated electrolytes like magnesium. They are widely considered safe and effective for remineralizing water or supplementing minerals, though you should choose products from established brands that emphasize third-party testing and transparency. Be aware that these products are often very salty and require dilution, and those on sodium-restricted diets should specifically look for low-sodium formulations.