Why do ice cubes sink in water?

You can - if you push it down! LOL, but no because the density of water decreases when energy is took away unlike most substances. When energy is being took away it gets denser and denser until it hits 4 degrees celcius. Then the density starts to decrease again. This a miracle of nature because if water did not do this fish would die every winter since the water would not only be at the top.

---An ice cube of deuterium oxide (containing a heavier isotope of hydrogen) sinks in water [ http://jchemed.chem.wisc.edu/JCESOFT/CCA/CCA2/MAIN/ICECUBE/CD2R1.HTM ]

well what if the water was really hot making it less dense