The ocean is dark, and it covers most of the earth, and whales live in all of it. The sounds guide them through that, and they talk to one another across oceans.
-- Grandpa (chapter 1)

Importance: This quote comes very early on in the novel, when Grandpa is telling Iris about the sei whale that gave her her name. He talks about how whales find themselves in the ocean, significant because both he and Iris are deaf. However, as Iris explains later on in the novel, she can still "hear" whales in a way that is different from how people who hear can. This also becomes significant shortly because of Blue 55's inability to talk to other whales across oceans. This quote is likely part of the reason why Iris feels so strongly drawn to Blue 55.

Blue 55 didn’t have a pod of friends or a family who spoke his language. But he still...
-- Narrator (Iris) (chapter 3)