Why is ice floating?

Ice floes, floating on non-frozen water, can exist, because ice has smaller density and weights less than water of the same volume in a liquid state. This is the reason why the surface of water is covered by lighter ice layer.  
In the polar areas, the frozen water creates ice mountains. The largest ice mountain was recorded in 1956 at the south Pacific. Its surface was over 31 000 km2 – about 1/10th of Poland’s surface!