In 1952, at age sixteen, Sylvia Earle—then a budding marine biologist—borrowed a friend’s copper diving helmet, compressor, and pump and slipped below the waters of a Florida river. It was her first underwater dive. Since then, Earle has descended to more than 3,000 feet in a submersible and, despite beginning at a time when few women were taken seriously as marine scientists, has led or participated in expeditions totaling more than 7,000 hours underwater, and counting. Equal parts memoir, adventure tale, and call to action, Sea Change: A Message of the Oceans has become a classic of env.