 Amphibious animals transition seamlessly between two different worlds. This new dual-fin robot might one day help machines do the same. Reported in the Journal of Bionic Engineering, this robot is inspired by the undulating motion of stingrays. As verified by finite element simulations, the robot uses a system of metal springs to control a thin, silica gel membrane for propulsion under water and on land. The ability to transition seamlessly between environments differentiates the robot from other amphibious designs, which typically have to switch between two methods of propulsion. Although currently slow, ongoing work is likely to improve the robot's efficiency, which combined with its low-weight design could make this amphibious machine a powerful aid for research and emergency services.