How did life begin? It is a question so fundamental that it has been pondered since the dawn of human civilization. As scientists have sought answers to this question and its logical derivative – Are we alone in the universe? – a common strategy, “follow the water,” has emerged. In this presentation, I will discuss recent efforts to understand the vital role of solute-laden, “salty” waters in fostering habitability on ancient Earth and Mars. I will focus on the ways that water-driven geochemical reactions generate habitable conditions, and their potential for originating Earth’s first organisms. My discussion will be informed by intensive study of modern and ancient hydrothermal systems, geochemical and geophysical surveys of unique, saline lakes in British Columbia (Canada), and the Mars Science Laboratory Curiosity rover’s ongoing exploration of Gale Crater, Mars.