Okay, internet—I'm not going to let you break my heart again. I know this is almost certainly fake—the product of a CGI firm. But even so, it's beautiful and amazing, and you can't rob me of that.
Let's put realism aside for just a moment and imagine a world in which boats swim through rivers, skimming out pollutants through natural biological filters (plants). Now let's up the ante, and shape these boats like whales.