As oceanographers contemplate a renewed commitment to ocean exploration (National Research Council, 2003), Helen Rozwadowski has given us a book chronicling the importance of discovery and exploration in the early Anglo-American roots of oceanographic science. Prior to the mid-19th century (approximately 1830-1880), what lay beneath the ocean’s surface was a great mystery, fertile ground for the imagination and superstitions of mankind. During these dark ages, navigators considered the deep sea to be anywhere that their 100-fathom sounding lines failed to touch bottom. Furthermore, while incredible monsters and denizens of the deep were believed to inhabit the sea, most naturalists thought that ocean life could not survive at depths greater than 300 fathoms. Remarkably, in less than 150 years, ocean explorers and scientists would go on to visit the great depths of the Marianas Trench and discover the amazing communities of deep-sea animals living entirely off the inorganic chemicals spewed forth from the hydrothermal vents of mid-ocean ridges. How did ocean exploration and science emerge from a seafaring tradition in which mariners attempted to minimize their time at sea and rarely strayed from proven trading routes? In her timely and carefully researched book, Rozwadowski answers this question not only by documenting the people and events involved, but also by providing the societal context for this 19th century period of ocean enlightenment.