Gives a historical account of how and why elephant seal populations were hunted to near extinction and how Mexico and the US worked to protect rookeries. Describes interactions between people and elephant seals at Año Nuevo, including humans "jumping on the elephant seals and riding them," leading to restriction of access and guided tours. Vividly describes elephant seal mating behavior, including statistics on pups and harems. Discusses ways elephant seal physiology confounds scientists, including their resistance to infection, their tendency to stop breathing while asleep, and their ability to dive very deeply for long periods of time, and speculates on what these scientific mysteries imply for medical research.