Abstract: A speed control apparatus for a waterway traveling vehicle which can guide the vehicle when it is traveling along the waterway, while applying a damping force to slow or stop the vehicle. A turning frame is provided in the waterway and is guided by a guide member for angular movement. The turning frame is urged by a spring mechanism to align in a predetermined direction, and the damping mechanism is mounted on the turning frame. When the vehicle approaches the damping mechanism obliquely, the turning frame is angularly moved to make the damping mechanism align with the direction of vehicle travel. The damping mechanism is then returned to a predetermined direction under the restoring action of the spring mechanism. In this manner the direction of the vehicle is corrected to the proper direction and is slowed or stopped by the action of the damping mechanism.