Anything that floats on water has a density less than water. Here are some examples:

* Wood: Most types of wood are less dense than water.

* Plastic: Many types of plastic, like styrofoam, are very light and float easily.

* Oil: Oil is less dense than water, which is why it floats on top of water.

* Air: Air is much less dense than water, which is why bubbles rise to the surface.

* Ice: While solid water, ice is actually less dense than liquid water, which is why it floats.

Let me know if you'd like to know more about density and why some things float!