Growing evidence, based on observations from orbiters, landers and telescopes, indicates that Mars may still have numerous hidden water reservoirs. Moreover, from the point of view of habitability, Mars is a prime target for astrobiologists in search of extant or extinct microbial life because we know that life exists in earth s permafrost regions, such as parts of Siberia and the Antarctic, which are the closest terrestrial analogues to Mars. Water on Mars and Life surveys recent advances made in research into water on Mars together with its astrobiological implications....