This is a film that I saw as a stage play in elementary school. It takes place mostly underwater or at least around water, and I believe it to be a disney film. It has a female character in it and she befriends a dolphin who has a whale mother figure called mother mother. The villians are a white ghost like being and has undersea grim reaper like henchmen. They recite this song in the film, sea magic of the deep blue sea, sea magic she tubba sea, or something like that. The white ghost does something with a net and kills mother mother.