Around a distant star in a distant galaxy, there’s a planet whose surface is covered by a dense, black water. The tides of its moon and sun raise its ocean in titanic swells that scrape the clouds and lumber slowly across its face. The waves don’t break—there’s nothing to break them—and so if you’re careful, you can plant yourself in a dinghy or a raft right at the trough and ride it up, up, up to the summit, where you can look out and see the world.