Shark Attack!
There is a pond outside of our office building which I can see from my cube. One of my co-workers thought it would be fun to have a remote controlled vehicle to play with here.
The shark wiggles its back fin for propulsion and used a fan in its head to enable it to dive. The fish would swim with it and touch it from time to time.
Here's a link to it: http://www.iwantoneofthose.com/search.do?productCode=RCSHAR#top, be sure to watch the movie.