What can the humanities reveal about people’s interconnections with the ocean, past and present? In 1975, the maritime historian Benjamin Labaree offered an influential argument that the Atlantic acted simultaneously as bridge and moat for European settlers of North America. The paradox of these overlapping functions provided a touchstone for understanding the maritime realm, but it is time to recognize the ocean as more than the flat surface implied by it. Two further pairings, repository–mirror and destination–home, testify to the duration of the human connections with the sea, including its depths, and also to the distinct ocean relationships forged by different cultures. The blue humanities provide a mooring for considering not only the ocean’s past and present but its future as well.