Ice is just solid water. When liquid water gets cold enough, it freezes and becomes a solid. Think about making ice cubes. You put water into a tray and place it in the cold freezer. Wait a while and you have ice cubes.
Look carefully at those ice cubes. Do you notice anything?
Right again! The ice cubes take up more room in the tray than the liquid water did!
Water is very special. It gets bigger when it freezes. This is also why ice can float in water.
Ice cubes aren’t the only example of floating ice in our world. Think about lakes and ponds in the winter. If it gets cold enough, a layer of ice floats on top of the water.
At the North Pole and South Pole, there are many examples of floating ice. In places like Antarctica and Greenland, glaciers can slowly move out over the ocean water and float there. When this happens, we call the floating ice an ice shelf. Sometimes, pieces of ice calve off the ends and form icebergs.

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