Saturn Is Less Dense Than Water

Density is how much mass is packed into a given volume. An object that is less dense than water floats in it, and one that is denser sinks. NASA states that Saturn is the only planet in our solar system with an average density that is less than water. To make the point, NASA adds that the giant gas planet could float in a bathtub, if such a colossal thing existed. The comparison is an illustration and not a real experiment, since no body of water could hold a planet. The word average matters as well. It describes the planet taken as a whole, and it does not mean that every part of Saturn is lighter than water.