1. The novel’s first line is: “The deep sea is a haunted house: a place in which things that ought not to exist move about in the darkness.” How does that image set the tone for the novel to come? What role do ghosts and hauntings play in the story?

2. There are several flashbacks to Miri’s mother and her eventual death. What effect do you think the mother has on Miri and her relationship with Leah?

3. The novel alternates between Leah’s and Miri’s perspectives. How are their styles of narration and worldviews similar and different?

4. Miri says that she had assumed that “alone was somewhere you could go, rather than somewhere you had to be left.” How do Miri and Leah each experience aloneness? Is that the same as loneliness for them?

5. What do you make of Leah’s employer, The Centre for Marine Enquiry? What do you believe the true purpose of Leah’s mission was?

6. What are the dynamics between Leah, Matteo, and Jelka on board, and how do they each react to their circumstances?

7. Leah tells us that she doesn’t know who she is writing for: “I’m not sure I really want [Miri] to know about it. I can’t say whether this is a story I actually want to tell.” Why do you think she writes down her memories of the mission?

8. Before she goes out the escape hatch, Jelka is convinced she hears a voice speaking to her. After her death, Leah begins to hear it, too. How do you interpret the voice?

9. Were you drawn more to one character than the other? How did the dual-voice structure affect your reading experience?

10. What is a sea lung, and what is its significance in the novel? What does it represent for Miri, specifically, and what does it suggest about the nature of transformation and flux?

11. Do you think Miri made the right decision in releasing Leah into the sea at the end of the novel? What do you think the future holds for each of them?