Researchers at the University of Bath have used nature for inspiration in designing a new type of swimming robot which could bring a breakthrough in submersible technology. Conventional submarine robots are powered by propellers that are heavy, inefficient and can get tangled in weeds. In contrast Gymnobot, created by researchers from the Ocean Technologies Lab in the Universitys Department of Mechanical Engineering, is powered by a fin that runs the length of the underside of its rigid body; this undulates to make a wave in the water which propels the robot forwards. The design, inspired by the Amazonian knifefish, is thought to be more energy efficient than conventional propellers and allows the robot to navigate shallow water near the sea shore.