DescriptionThis thesis describes the design, fabrication, and characterization of a soft robotic jellyfish. Living jellyfish are some of the most efficient swimmers in the ocean and exhibit unique capabilities for manipulating fluid flows for efficient propulsion. The fabricated soft vehicles in this work emulate some of the characteristics of living jellyfish and their propulsive mechanisms have the potential to influence the future design of efficient underwater vehicles. With respect to fabrication, the author uses silicones of varied hardness to mimic the flexibility and shape of biological jellyfish. Characterization and testing of the biomimetic vehicles facilitate comparisons to living jellyfish and provide physical insights into the dependence of efficiency on timed gaits and formed vortices. Based on calculated costs of transport, a slow gait results in the highest locomotive efficiency. These results suggest that further optimization of the designed vehicles and gait will yield future propulsion systems with even higher efficiency.