Upon completing his historic work on the Human Genome Project, J. Craig Venter declared that he would sequence the genetic code of all life on earth. Thus began a fifteen-year quest to collect DNA from the world's oldest and most abundant form of life: microbes. Boarding the Sorcerer II, a 100-foot sailboat turned research vessel, Venter traveled over 65,000 miles around the globe to sample ocean water and the microscopic life within. In The Voyage of Sorcerer II, Venter and science writer David Ewing Duncan tell the remarkable story of these expeditions and of the momentous discoveries that ensued--of plant-like bacteria that get their energy from the sun, proteins that metabolize vast amounts of hydrogen, and microbes whose genes shield them from ultraviolet light. The result was a massive library of millions of unknown genes, thousands of unseen protein families, and new lineages of bacteria that revealed the unimaginable complexity of life on earth. Yet despite this exquisite diversity, Venter encountered sobering reminders of how human activity is disturbing the delicate microbial ecosystem that nurtures life on earth. In the face of unprecedented climate change, Venter and Duncan show how we can harness the microbial genome to develop alternative sources of energy, food, and medicine that might ultimately avert our destruction.