Given the facts that a vast area of the earth is covered by water and the average depth of the oceans is more than 3,000 m, the issue of the unknowns beneath the water surface is a challenging and questionable one. It has been a few decades since remotely operated vehicles as well as untethered underwater robots have appeared and elevated the level of complex engineering. In this category, underwater robots that mimic fish and aquatic creatures open new horizons. In this article, imitating the body shape, kinematics, and swimming mechanism of a batoid fish (Dasyatidae), a vessel is designed that can swim at an acceptable speed with a limited amount of power. The hull shape is based on a cardioid curve, and drag force is calculated using fundamentals of fluid mechanics. Propulsion of the robot-fish is two wings at starboard and port that are undulating backward; thrust is approximated versus shaft speed. Finally, the power for swimming at the design speed is evaluated and compared with the available data of similar orders of magnitude.