Reviewed by: Vast Expanses: A History of the Oceans by Helen M. Rozwadowski Penelope Hardy (bio) Vast Expanses: A History of the Oceans. By Helen M. Rozwadowski. London: Reaktion Books, 2018. Pp. 268. Hardcover £16. Helen Rozwadowski has long been an evangelist for the idea that the oceans themselves have a history, and one to which historians and their publics should pay increased attention. Where her previous volumes have provided meaningful contributions to this history, this masterful new book serves both as a well-argued extended essay renewing the call and as an insightful response to it on a broader scale than before. Specifically, Rozwadowski argues that the human relationship with the sea extends back to our evolutionary ancestors. That relationship grew closer and more complicated as the modern world industrialized and globalized. To understand its history, she says, we must pay attention to the ways in which humans have historically formed knowledge of the oceans—a category in which she includes experiential, scientific, and imaginative ways of knowing. Throughout, she presents the ocean as three-dimensional, as the human relationship with the ocean's depths and inhabitants forms an important facet of her argument. Rozwadowski explores the story of humans and the oceans over the truly longue durée: the Earth forms and oceans coalesce on the first page of chapter one. While several billion years of history in 200-odd pages might seem a whirlwind, the story is well woven, with each chapter covering a new era of the human-ocean relationship in which there are both new kinds of knowledge and new methods of knowledge gathering. She emphasizes history as a work in progress, addressing, for instance, recent revisions to archaeological understanding of the peopling of the Americas, and she smoothly intertwines history with paleontology, archaeology, and earth and ocean sciences in a style that is neither overly technical nor pedantic. As the book proceeds, each chapter covers a shorter time period—usually with a closer focus, though this remains a global history throughout. [End Page 1098] The first chapters move from geological history to evolutionary migration to commercial seafaring and expansion, and in the latter she flips the usual story, arguing that the voyages of the fifteenth and sixteenth centuries were important less for finding new lands than for finding sea routes between the old ones. With the dawn of the industrial revolution, she explains, the oceans too were industrialized as a workplace, leading to intensification of their traditional uses as well as new uses driven by modern science and engineering. Industrialization led fewer people to be involved in extractive work that was thus increasingly invisible to the general public, leading many to consider the ocean something apart from their regular lives, timeless and outside of history. As later chapters show, however, the modern ocean has become increasingly accessible to the public, both through recreation and popular media, and Rozwadowski explores how this led to marine areas and species being fit into (or ignored by) various phases of the environmental movement. This book fits squarely at the intersection of environmental history and history of technology, as Rozwadowski's argument that knowledge mediates the human relationship with the sea means ocean history is highly technologically contingent. However, it is by no means technologically determined; in Rozwadowski's telling, humans use technologies from fishing gear to navigational instruments to SCUBA to know the ocean, but they choose to do so—and choose how to use the knowledge thus acquired—for varied cultural reasons. Historians of science, labor, transportation, and recreation will find much of interest here. The book is well-organized, highly readable, and thoughtfully authoritative, making it equally useful for academic historians interested in her call to take ocean history seriously and for those less expert, including both undergraduates and general readers. It is light on footnotes (which might play well with those latter audiences) but integrates references to relevant historiography within the text itself; frequent black-and-white illustrations usefully supplement the text. All in all, Vast Expanses provides a stimulating rethinking of our approach to the oceans and an important addition both to the growing body of scholarship on ocean history and to the broader...