Water displacement can be explained by the law of buoyancy, which states when an object is immersed in a fluid that has a greater density than the object itself, the level of the fluid will rise. To calculate the amount of displacement, determine the difference between how much the submerged object weighs and how much the displaced fluid weighs.
As a result of the law of buoyancy, heavier objects that fail to displace a significant amount of water often sink to the bottom of the liquid. Meanwhile, lighter objects that displace water tend to float on top. Objects that float have a lower density than water.