Family Drama, Adventure, Coming of Age, Young Adult
Q: What do you get when you put together a recently dead mother, an unstable father, and three brothers who'd do anything for one another?
A: A family drama.
In The Great Wide Sea, the Byron family's intense emotional stuff is echoed by their outdoor travels, which are also extremely dramatic. As Ben and his brothers fight the elements, the angry ocean, and a hungry shark, they also fight among themselves.
The family drama, the adventure—it's all connected. (Well, except for the shark. That guy's all on his own.)
After Jim Byron goes overboard, his sons suddenly find themselves orphaned. (Of course, we know that Jim will resurface at the end of the novel.) The Byron brothers learn to fend for themselves; when Jim finally reappears, Ben tells him,
I got hair on my chest while you were gone. (40.41)
And no; he's not just talking about growing out a luscious set of pectoral curls.
The book's focus on the kids' maturation—especially Ben's—puts it firmly in coming-of-age territory, which is why you'll find it shelved with the Young Adult books.