![Floating ice in sea.](http://static.sciencelearn.org.nz/images/images/000/000/767/full/Sea_ice_viewed_from_the_aircraft_Megan_Balks.jpg?1674164882)
Water density changes with temperature and salinity. When water freezes at 0°C, a rigid open lattice (like a web) of hydrogen-bonded molecules is formed. It is this open structure that makes ice less dense than liquid water. This is why icebergs float.