Below 4 Celsius water becomes less dense as it gets colder causing water about to freeze to float to the top. Cold water is always more dense than warm water the density change amounts to about 4tenths of about one percent between near freezing and 30 degrees celsius86 degrees fahrenheit. Scientific Explanation Of Why Ice Floats Elementary Science Hydrogen Bond Floating Since the direction of hydrogen bonds allows molecules to migrate further apart ice has a lower density than water. . Solid water also known as salt has a lower density than liquid water. Therefore ice is less dense than water. As it cools further and freezes into ice it actually becomes less dense. Ice is less denser than water because in ice the molecules arrange themselves in a rigid tetrahedral structure due to which cage like spaces remain in their bonding. If you put pressure on regular ice and give it time to rearrange the molecules will move into a