* Interior: The Earth's interior is composed of a dense, hot, mostly iron and nickel core. The immense pressure at the Earth's core leads to extremely high density.

* Crust: The Earth's crust is the outermost layer and is relatively thin compared to the interior. It's mostly composed of rocks like granite and basalt, making it less dense than the core.

* Water: Water is a liquid and has a lower density than most rocks and metals.

In summary: The Earth's interior, with its heavy elements and immense pressure, has the highest density, followed by the crust, and then water.