Water can sink in water?

Yes, water can in fact sink in water.  Since sinking or floating is a matter of density, water just had to be more dense than water... But wait how can something be more dense than itself!? Well differences in temperature is the answer.  When a substance is cold, it comes closer together and the molecules move slower to make it more dense, as opposed to being hot and more spread out.  The green water in this picture is ice water and the clear water was kept at room temperature. What we did was put some of the dyed cold water into the clear room temperature water and it settled at the bottom.  This means that the cold water must be more dense than the room temperature water which makes perfect sense because when a substance is cold, it becomes denser.