A scientifically grounded look at the destructive power of the most important element in human survival: water. We explore the terrifying consequences that flash floods and rising sea levels could have on global populations, as experts explain how a massive volume of water might come to earth from space, and wreak havoc once it arrives. We examine several ways we could fight the rising tide: building immense seawalls to protect entire cities, underwater habitats, and finding new ways to live on the surface of the sea. As the ground begins to vanish beneath our feet, we'd be forced to look at new ways to live on a planet that is becoming a water world – but how long can we keep our heads above water? Is there hope for mankind to survive? Our ability to adapt may be our ultimate salvation.