Environmental historians have forged sophisticated understandings of interrelationships between humans and many parts of the natural world. The oceans -especially the great depths and the open seas -remain a challenge. In 1864, Henry David Thoreau expressed deeply held cultural assumptions about the timelessness and imperviousness of the sea:We do not associate the idea of antiquity with the ocean, nor wonder how it looked a thousand years ago, as we do of the land, for it was equally wild and unfathomable always. The Indians left no traces on its surface, but it is the same to the civilized man and the savage. The aspect of the shore only has changed. (1896: 85) This apparent contrast between land and sea continues to hold sway; the ocean remains to many "empty of history, utterly without a past" (Stilgoe 1994: 30).To the extent that historians have begun, recently, to turn seaward, the view seems always to include land as well as sea -islands, beaches, littoral environments, and ocean basins with an emphasis on rims. Scholars who take seriously the aims of environmental history must also seek to historicize the ocean itself, including its most remote parts, because even those are as intertwined with human history as the far corners of the terrestrial world. Similarly, histories of the ocean that deal only with oceanic peoples or those engaged in maritime work will never be as comprehensive as those that also succeed in accounting for the myriad other groups of people who interact with the ocean -consumers, writers, scientists, recreationalists, policymakers, dreamers -some of whom never even see the ocean. This essay situates