At 82, Earle is America’s most distinguished oceanographer and marine biologist, and now its most fervent champion for ocean conservation. She estimates that in the time since her first dive, aged 16 – clamping on a sponge-diver’s helmet and descending 30ft to the bottom of the Weeki Wachee River in Florida – she has spent close to a year underwater, at times for 14 days at a stretch, living on the bottom of the ocean in research installations.