This is a cool project by the people at Festo. They actually built a robotic penguin that uses a type of 3D sonar to help orient itself in the water. The penguins are built and programmed so well that they can communicate between themselves to avoid collisions. The most interesting thing about it is that from far away they look like real penguins. Check out the video, see if you can tell the difference.
Photo Credit: Festo
"Like its natural archetype, the AquaPenguin from Festo has a hydrodynamic body contour. Its elegant wing propulsion and its head and tail sections, which can be moved in all directions, allow the robotic penguins to manoeuvre in cramped spatial conditions to turn on the spot when necessary and – unlike their biological counterparts – even to swim backwards."