High Heat of Evaporation
When water boils, it evaporates. Converting one gram of the hottest liquid water into a gas requires 540 calories of energy (that's a lot!). This large amount of energy is needed to break the hydrogen bonds that keep water in a liquid state. This high heat of evaporation is important for living things because it provides an efficient way to release excess body heat. When an animal sweats ro splashes itself with water, body heat (energy) is used to vaporize the water, thus cooling the animal.