Here's why:

* Salt dissolves in water: When salt (sodium chloride) dissolves in water, it forms ions (sodium and chloride). These ions take up space between the water molecules.

* Increased mass: The salt ions add to the overall mass of the solution, increasing its density.

* Density = Mass/Volume: Since the mass increases and the volume remains relatively the same, the density of the saltwater solution increases.

This is why objects float more easily in saltwater than in freshwater. The higher density of saltwater provides more buoyancy.