There were several of these with different themes like Ring toss, pac man and Mr. mouth. Each had some objective to complete or on the two player versions you were trying to outscore your friend. It would have been a cool idea but in reality it was just a kid spasmodically pushing the pump button. There was some technique of light pump then hard pump or whatever, sound like I am getting into a strange area now. But in reality it was just a single button aquatic video game. It ends up making the Atari's joystick look like a state of the art device.
They were great in cars, well until the game boys was released. This is one of those toys I just never see making a comeback. None of the art of Spirograph, none of the making stuff like creepy crawlers and none of the fine motor control of the Sears Giant Crane.