From Kate Chopin's The Awakening to Finding Nemo, the ocean often shows up when freedom and coming home are on the literary table. The Forest of Hands and Teeth grabs a plate and loads up at that symbolic feast. For many of the characters, the idea of the ocean is their dream for something better, yet what that "ocean" is depends on the character.
Let's start with our girl Mary. Her dreams of the ocean began as a little girl when her mom told her stories about how the world used to be. She even had a picture of her great-grandmother, free and happy as a child in the waves. So when Mary thinks of the ocean, she thinks of "a world without the Unconsecrated, a world without the Forest of Hands and Teeth" (1.5). To Mary, that's real freedom, and that freedom is the only thing that can make her happy. If you want to know just how obsessed she is with the idea, hop on over to the "Characters" section and read all about the Marymeister.
Travis, on the other hand, started dreaming of the ocean when he met Mary and heard her stories. At first he was all about escaping and finding the dream world she talked about, but then his dreams started to change, thanks to a bum leg and his overwhelming love for Mary. The ocean didn't mean surf and turf to him at that point. His "ocean," his dream, became a life with Mary. He gets it, too—when he and Mary get holed up in the house, Travis finds his ocean. He says, "Those days back there, in the house, that is my world. That is my truth…. That is my ocean" (31.27). And thank goodness, since he sacrifices himself to the zombies a few days later.
And then there's Cass. She's not a believer in Mary's stories, and she's not a fan of the ocean because she doesn't see a way out of the zombie world. In her words, "It's like we were told growing up—there is no end to the Forest of Hands and Teeth!" (20.52). She figures it's best to deal with the lemon tree they've got, rather than continuing to search for a mysterious lemonade tree of ocean-ness. Freedom from zombies? That's ridiculous. Hope for the future? Even more far-fetched. The ocean? A big sack of stupid.
The ocean, then, is not only the dream of a better world, but it's a place to call home. Mary aches for it, Travis feels it, and Cass doesn't believe it exists. In some respects, they are all right.