Sure, this may be a fairly simplistic story, with unimpressive artwork and less-than-stellar animation, and it may be heavy-handed on the moralizing, aimed at kids in the eight to ten year age range. But overall...not that bad. It's hundreds of years in the future, and Earth has turned into a Waterworld, mostly ocean and humans living more in harmony with nature (out of necessity). Elfie, with her brother and grandfather live a seemingly peaceful life, flitting about (and under) the seas in futuristic ski-doos, playing with the dolphins and worrying about the growing encroachment of their nation's development on thepristine seas.

Unexpectedly Elfie discovers she can breathe under water, and soon becomes hopelessly entangled in the middle of a conflict between the humans above the sea (led by Ming the Merciless) and the mythical and much-feared undersea folk.

It's not a very sophisticated story, which is fine, not every story has to have some big twist or multi-faceted relationship polygon. The ending is somewhat abrupt and deus-ex-machina in nature, but oh well. Good story for the younger set, and their adult parents will probably be okay with it, too.