Here's why:

* Density: Ice is less dense than both fresh water and salt water. This means ice takes up more space for the same amount of mass.

* Buoyancy: Objects float when they displace an amount of liquid that weighs more than the object itself. Because ice is less dense than water, it displaces enough water to support its weight, causing it to float.

* Salt's Effect: While salt water is denser than fresh water, the difference in density is not enough to make ice sink. Ice is still significantly less dense than salt water.

So, even though salt water is denser, the principle of buoyancy still applies, and ice floats in it.