The little boy who brings his line to the old fishing hole uses a piece of cork as a “floater” without ever wondering what keeps that piece of cork bobbing on top of the water. But the capacity of cork to float has been known since ancient times, and cork life-preservers saved many a life thousands of years ago!

Cork is much lighter than water. The reason it floats is that water does not easily penetrate the walls of the cells, which are filled with air. This prevents the cork from becoming water-logged and sinking.