Why Do Things Float?

To float, an object needs to be less dense,, needs to weigh less than a sack of water the exact same size. An object’s floaty-ness is also called buoyancy. If something floats, it’s buoyant. If it sinks, it’s non-buoyant. And if something is exactly as dense as the fluid around it, we say it has neutral buoyancy—and it can hang in the water like a fish.