This interactive 3D physics simulation demonstrates how the volume of water overflowing from a full container can be used to measure the volume of a submerged object. It also shows the special case of a floating object, where only part of the object is submerged.
For objects that sink, the displaced water volume is equal to the object's full volume.
For objects that float, only the submerged part displaces water. The displaced water weight equals the object's weight.
Objects with density lower than water float, while objects with density greater than water sink.