Place a cube of ice in a tumbler and fill it to the brim with water. The ice cube floats and partly projects from the surface. Will the water overflow when the ice cube melts!The water increases its volume by one eleventh when it freezes. The ice is therefore lighter than water, floats on the water surface and projects above it. It loses its increased volume when it melts and exactly fills the space, which the ice cube took up in the water. Icebergs, which are a danger to navigation, are therefore especially harmful because one only sees their tips above the water.