If you go to Skógafoss—a waterfall in the south of Iceland—when the full moon is shining bright during the aurora season, perhaps you would catch this magical scene. And meet an elvish princess who looks like Björk.
This is not a rainbow. It's a moonbow, an extremely rare atmospheric phenomenon caused by the near-full moon that it's extremely hard to catch. So hard, in fact, that you can only see its colors thanks to long-exposure photography.