Why is it that scuba divers and surfers are some of the strongest advocates of ocean conservation? Because they've spent time in and around the ocean, and they've personally seen the beauty, the fragility, and even the degradation of our planet's blue heart.

We need to respect the oceans and take care of them as if our lives depended on it. Because they do.

As a child, I was aware of the widely-held attitude that the ocean is so big, so resilient that we could use the sea as the ultimate place to dispose of anything we did not want, from garbage and nuclear wastes to sludge from sewage to entire ships that had reached the end of their useful life.

Humans are the only creatures with the ability to dive deep in the sea, fly high in the sky, send instant messages around the globe, reflect on the past, assess the present and imagine the future.

Some experts look at global warming, increased world temperature, as the critical tipping point that is causing a crash in coral reef health around the world. And there's no question that it is a factor, but it's preceded by the loss of resilience and degradation.

I hope for your help to explore and protect the wild ocean in ways that will restore the health and, in so doing, secure hope for humankind. Health to the ocean means health for us.

Health to the ocean means health for us.

When I write a scientific treatise, I might reach 100 people. When the 'National Geographic' covers a project, it communicates about plants and fish and underwater technology to more than 10 million people.

Every time I slip into the ocean, it's like going home.

With every drop of water you drink, every breath you take, you're connected to the sea. No matter where on Earth you live. Most of the oxygen in the atmosphere is generated by the sea.

Any astronaut can tell you you've got to do everything you can to learn about your life support system and then do everything you can to take care of it.

Ten percent of the big fish still remain. There are still some blue whales. There are still some krill in Antarctica. There are a few oysters in Chesapeake Bay. Half the coral reefs are still in pretty good shape, a jeweled belt around the middle of the planet. There's still time, but not a lot, to turn things around.

For humans, the Arctic is a harshly inhospitable place, but the conditions there are precisely what polar bears require to survive - and thrive. 'Harsh' to us is 'home' for them. Take away the ice and snow, increase the temperature by even a little, and the realm that makes their lives possible literally melts away.

No water, no life. No blue, no green.