This is amazing. I mean - really, genuinely amazing! (To me, anyway.)
Last month, a radio-controlled model airship regatta was held in Friedrichshafen in southern Germany. There were plenty of enthusiasts in attendance, with the usual variety of model airships - but along came Empa, a Swiss materials technology development institution, and blew them all away!
Professor Paolo Ermanni and four students, Christa Jordi, Silvain Michel, Laurent Wahl and Nicolai Widmer, all from Empa, developed a fish-shaped airship that actually 'swims' through the air. Its tail propels and steers it, and it's supported by the gas inside it, aided by its pectoral fins, which can act as lifting or steering surfaces. Electro-active polymers are used to power the tail. When an electric current is applied to them, they contract like a muscle, giving the tail a kicking motion. (For those interested in the technology, there's a brief explanation here. It's a one-page PDF file, summarizing the research used to make this airship, which was part of a Ph.D. submission).
Enjoy this remarkable video as an airship literally 'swims' through the air.
Like I said - amazing!