From space our planet is blue, and life here has evolved in the presence of abundant water. However, on land, water remains one of life's major challenges. Fully two-fifths of the land surface is classified as arid: the hot and cold deserts, where water is largely unavailable. Even in biomes where water availability is generally good, seasonal, daily and sporadic conditions can mean that life has to be able to survive its absence. Surprisingly, some organisms are able to survive complete loss of all their body water, to undergo anhydrobiosis. This surprising ability has evolved many times, and is particularly prevalent in very small animals. The biochemistry of anhydrobiosis challenges ideas of what ‘being alive’ really means and promises exciting biotechnological applications.