Water is polar: Oxygen holds its Hydrogen bonds strongly (covalent bond) so much that it polarizes it towards the oxygen (oxygen is highly “electronegative”).
As a molecule whole, Hydrogens are + and O2 are – so a second bond forms between the molecules allowing ice to float—a new lattice. It also creates a high heat capacity (holds heat) allowing for thermoregulation and a conduit for metabolism to occur. It dissolves materials as well. Water is a good solvent because it is polar (having a + and – side on the molecule). It breaks solutes (NaCl) into its parts.
Simulations from the University of Colorado: