Dubbed "Her Deepness" by the New Yorker and the New York Times, award-winning oceanographer, conservationist, and National Geographic explorer-in-residence Sylvia Earle boasts an amazing list of above- and below-water accomplishments, including leading more than 100 marine expeditions, captaining the first all-female research team to live underwater, setting several deep-sea records, and authoring more than 190 scientific, technical, and popular publications. Her latest book, National Geographic Ocean: A Global Odyssey, is a deep dive into the Earth’s many ocean realms, featuring scores of Nat Geo’s always impressive images, illustrations, and detailed maps, and the author’s lyrical and lively narration.

Earle likens Ocean to her own personal odyssey. “More has been learned about the ocean in my lifetime than during all of human history,” she says. “But at the same time, more has been lost. I hope to inspire people to want to know more—and to literally dive in, to see for themselves why the ocean matters to everyone, everywhere, all of the time. Then, to do whatever they can to restore and protect the planet’s ‘blue heart.’ ”

Earle accomplishes that goal by tracing the evolution of the ocean, and how it has literally shaped the Earth’s geography, chemistry, and biology, while providing an ecosystem for humans, coast-dwelling creatures, and some 200,000 discovered marine species. There’s no underestimating its importance. “The ocean,” Earle says, “drives climate and weather, generates most of the oxygen in the atmosphere, and is home to the greatest abundance and diversity of life known to exist.”

Earle introduces readers to some of that vast variety, as well as to numerous fellow scientists and ecological activists. She also outlines ongoing threats to the marine environment. “Some are readily apparent, especially the magnitude of the noxious things we put into the ocean and the magnitude of the innocent life we take out,” she says. “Less obvious but more important is complacency about degrading the systems that underpin our economy, health, security, and most importantly, life itself.”

A longtime advocate for conservation, Earle was named the very first “Hero of the Planet” by Time magazine in 1998, and in 2009, she won the $1 million TED Prize, enabling her to make a wish large enough to change the world: “I wish you would use all means at your disposal—Film! Expeditions! The web! New submarines!—to create a campaign to ignite public support for a global network of marine protected areas.”

She fulfilled that wish with the founding of Mission Blue, an organization that’s built a global alliance around ocean exploration and finding and preserving endangered marine areas, otherwise known as “hope spots.” “Natural areas notable for high diversity and high threat are known as ‘hot spots,’ ” she says. “So, it seemed to me that they should also be regarded as ‘hope spots’ when actions are taken to protect them.”

The continuing effort has been a success, and recently it became the subject of an acclaimed Netflix documentary, Mission Blue. “It is inspiring to see local champions and communities in 140 places globally respond with actions to help protect the ocean,” she says, “with many more in the wings.”

When asked what is one thing people can do right now to save the ocean, Earle says, “Everyday choices matter. What you choose—to eat or not, or wear or not, times a few dozen or a thousand or a billion—generates waves of behavior that can change the world. If you sing or have a way with words or math or art or with animals or plants or people, use the superpower that is yours alone and share it generously to make a difference.”

Ocean: A Global Odyssey also reminds us how connected we are to each other and to the planet. And that gives Earle hope. “The response to the Covid-19 pandemic demonstrated that people can swiftly change their behavior when their lives are threatened,” she says. “Our existence is now on the line because of what we are doing to alter the climate, the air we breathe, the water we drink, and the fabric of life—mostly in the sea—that has made Earth the only hospitable place in an otherwise extremely hostile universe. Now we know. Protect the living ocean as if your life depends on it—because it does!