In her 62 years studying the sea, the National Geographic Explorer in Residence has spent 6,500 hours exploring life underwater. She’s the only untethered diver ever to have dropped 1,250 feet to the ocean floor (though the bulky hardsuit looked more like a killer robot than a deep sea diver).

For years, “Her Deepness” has been the world’s leading advocate for ocean conservation. Besides teaming up with Google to launch Google Ocean, the only complete, interactive map of the planet underwater, this year she’s launched a campaign to create a global network of marine reserves to allow sea life to recover after a century of over-fishing.
—By Daniel Grushkin

National Geographic ADVENTURE: When did you realize that the ocean was being badly depleted by human activity?
Sylvia Earle: It has gradually dawned on me. The attitude of infinite resources in the sea was widespread. When I started out as a scientist years ago I just wanted to study my plants and the fish and the ecosystem because they’re beautiful and that was my passion. In hindsight, the clues were all over. Even the decline of all the big fish was obvious by the mid 1950s.

So you’ve made it your mission to alert the world to the crisis?
SE: It doesn’t matter whether you ever see the sea or touch the sea, the sea touches you everyday with every breath you take and every drop of water you drink. This clearly hasn’t dawned on most people around the world. But most people around the world haven’t had the opportunity to see as much as I have.

What’s it like to walk the bottom of the sea?
SE: It's like, ‘[give me] more'. It's never enough. It's a great awakening about how we're connected to all that’s there. Every moment underwater reaffirms the beauty of how all life ties together. We are a part of nature, not apart from it. Most people insulate themselves from that. Some of us are lucky enough to have immersed ourselves in it, and are so eager to share it. Children are receptive—it's my personal mission to find a child in everyone, to see the world different from the jaded inward-looking, selfish, human perspective that has gotten us into the trouble we're in.

Is there a favorite species down there that you love to watch?
SE: My grandsons splashing around in the ocean. Literally, I love them all. Everyone has a character and something completely fascinating, from the giant whale to the amazing diverse microbes that are difficult to see without magnification. They’re all living creatures that make up the tapestry of life. The glory is that we now have the capacity to see them and understand something about how this beautiful blue planet works.

What would you say to the consumer on the street?
SE: Well, I can say I have stopped eating fish completely. Give the ocean a break. Give fish a break. Give lobsters, clams, oysters a break, and see if we can begin to restore health to the ocean.

In April 2010, you’re hosting a seven-day TED conference on a ship off the Galapagos Islands. You’ve invited marine scientists, activists, even artists. What do you hope to achieve?
SE: Sixty-four percent of the ocean lies beyond national jurisdiction—the high seas. I hope to develop an initiative that would be successful this time in bringing about an overarching policy of ocean protection, and establish a network of protected areas within that space to counteract the destructive policies that are undermining it all.