The ocean is a powerful motif throughout the novel. It is often personified or otherwise characterized as a living entity; frequently invoked, alternately as inspiration and as threat; and indicative both of the natural world and of supernatural territory. Leah first compares the ocean to the moon: “Uneroded by atmosphere, by wind or by rain, any mark made up there [on the moon] could quite easily last for several centuries. The ocean is different, the ocean covers its tracks” (9). The ocean is cunning and mysterious. As Leah perceives it, the ocean is a place of constant metamorphosis that is wholly itself, unmarked by others. Leah is fascinated with the ocean and well aware that her love affair with the place is, at its heart, dangerous: “To know the ocean, I have always felt, is to recognize the teeth it keeps half-hidden” (46). This observation implies that Leah’s transformation, like that of a vampire or a werewolf, is engendered by the ocean’s fateful bite.

Still, the ocean is also a place of natural wonder. What draws Leah to it in the first place is its scientific value: “There was something I loved, aged twelve, about the way the book spoke so coolly of the deep ocean, not as something to be survived or conquered but simply navigated” (56).