Abstract: A swimming aquatic creature simulator having a body which propagates waves of undulation of and along that body to thereby propel the simulator through a fluid in a lifelike manner. The body is formed of an elastomeric material and may be shaped like a fish. Applying oscillating rotational motion to the body at a location forward of the center of mass of the body produces undulating movements of the body which propel the simulator. The oscillating motion input may be provided by twisting a rigid shaft or flexible cable, which is connected to the body at a point forward of the center of mass. An internal motor can also be used to provide the oscillating motion input.