I swam out, trying to swim through the rollers, but having to dive sometimes. Then in the quiet water I turned and floated. Floating I saw only the sky, and felt the drop and lift of the swells. I swam back to the surf and coasted in, face down, on a big roller, then turned and swam, trying to keep in the trough and not have a wave break over me. It made me tired, swimming in the trough, and I turned and swam out to the raft. The water was buoyant and cold. It felt as though you could never sink. I swam slowly, it seemed like a long swim with the high tide, and then pulled up on the raft and sat, dripping, on the boards that were becoming hot in the sun.
How does Hemingway use the style of his prose to reinforce the significance of this passage from Book III and reinforce the theme of the restorative power of the natural world?