Dive down, down through open ocean, past the sea turtles in the sunlight zone, through the twilight and midnight zones (watch out for the giant squid and the 400-year-old shark!), and into the abyssal zone. In most places, you’d be at the bottom of the ocean. But there’s an even deeper place below that bottom— the very, very bottom of the ocean, which we have only just begun to explore . . .