There is this old animated film that I saw around ten years ago (I think). I think it was a Japanese anime style, but I am not sure. I remember a girl out on a boat with her father or uncle or someone and she falls into the water (I think the ocean). She then gets tangled in some seaweed and can't get free. Just as she is about to pass out her hair changes color and then she can breath underwater. For the rest of the movie, every time she is out of the water her hair is the original color and when she is underwater it is the other color and she can breath. I think she ends up meeting others like her underwater. And I think she has to save something or someone in the end. This is all I can remember. Could someone please help? Thanks.