If we consider the first sentence of a story as the flagship sentence of a tale, then this opening line is an excellent example of what a flagship sentence should be. It has character, establishes a narrator; there's conflict and foreshadowing, and it is unusual and striking, setting the tone of the novel.
It continues with the second paragraph:
At all hours his roars reverberated, breaking into my sleep, rattling the windows.
So the impression we get early on is that the first sentence is not weakened by being a mere metaphor. Despite this short first chapter at a little more than a page being back story, there is conflict and questions are raised. This is the best kind of back story - back story that raises questions, and not back story that answers questions and makes everything clear on page 1.
Before part 1 begins, there is a brief one-page, one-paragraph insert that begins with ellipsis, indicting this is the end of some text. It explains the little known history of a book that seems to have been lost by 1368, called the Caravan Bestiary, a natural history of all beasts that were on earth at God's creation, including those that did not make it to Noah's Ark. As this is now a book about a book, I'm easily hooked. Others, of course may not be, but a mystery about a lost book with secrets is enticing.
First thing said:
"It scares away evil spirits when I'm at sea."