Journey to the Water Planet

A ball alien from the compressed air nebula is tasked to travel to the center of the water planet and retrieve the legendary golden pearl. They quickly find out that any object, totally or partially immersed in a fluid or liquid, is buoyed up by a force equal to the weight of the fluid displaced by the object. They are then relieved to find that, thanks to their superior knowledge of fluid mechanics, they can use the plentiful pieces of scuba gear that are mysteriously lying around to swim deepe...