Take a look at the robot AquaPenguins shown below. These robots were created by Festo as part of their bionic learning project. They navigate independently and can communicate with each other - just like real penguins!
This robot has a body that flexes in a remarkable way; it is much more than just a rigid "submarine" body with flippers attached (compare with the Robot Turtle Madeline, which is still cool, I'm just saying that flexible has its advantages).
Watch this remarkable autonomous underwater vehicle determine its position with 3D sonar. You'll enjoy the Festo robot AquaPenguin video below.
"The bionic penguins can become autonomous underwater vehicles in the water pool and have self-guided navigation. They have a 3D sonar, which, similar to dolphins, is used to communicate with the environment and other robot penguins as possible. For example, in order to avoid collisions.
An absolute novelty in the robot technology is a fuselage that moves in all directions. The hull design of the penguins in the automation can be as flexible tripod arrangement, and so used in handling equipment for factories or other applications.
I love underwater robots; see if you can find a new favorite: