In December 1872, HMS Challenger embarked on the first round-the-world oceanographic expedition. Its goal: to shine a light on the mysteries of the deep sea. For the next four years, Challenger's naturalists explored the oceans, encountering never-before-seen marvels of marine life. The expedition’s achievements are the stuff of legend. It identified major ocean currents and defining features of the seafloor. It measured worldwide sea temperatures and chemistry. And, most spectacularly of all, it collected nearly five thousand sea creatures and plants new to science. In The Wake of HMS Challenger, Gillen D'Arcy Wood looks afresh at this legendary scientific odyssey and shows why, 150 years later, its legacy looms larger than ever.

The Challenger's scientists had no way of knowing that the incredible undersea aquarium they were documenting was on the verge of catastrophic change. Off Portugal, they encountered a brilliant starfish now threatened with extinction by microplastics; in St. Thomas, teeming coral habitats that today have been decimated by ocean warming; and at remote Ascension Island, the breeding grounds of the now-endangered green turtle. The Wake of HMS Challenger offers a stunning before-and-after picture of our oceans. It is both a reminder of what we have lost and an urgent call to preserve what remains of our planet's final frontier.