Motor-Free, Transparent Eel Robot Swims Silently Underwater

University of California  engineers have created an eel-like robot that can swim silently in salt water without an electric motor. The foot-long robot uses artificial muscles filled with water to propel itself. The virtually transparent bot is connected to an electronics board that remains on the surface. One key innovation was using the salt water in which the robot swims to help generate the electrical forces that propel it.