Throughout all of human history we've enjoyed certain benign circumstances: an envelope of atmosphere, an envelope of temperature. A kind of resilience that if you cut down trees, then they'll grow back. You take fish, they recover. You put stuff into the atmosphere that you know is not good for us, but we can still breathe. We haven't awakened, generally, to the sense of urgency that does exist.

Many of us ask what can I, as one person, do, but history shows us that everything good and bad starts because somebody does something or does not do something.

The observations that have developed over the years have given us perspective about where we fit in. We are newcomers, really recent arrivals on a planet that is four and a half billion years old.

Globally sharks have been killed for their fins, for their cartilage, for their livers, for their meat. But mostly what has driven some species of sharks to near extinction - including the hammerhead shark - is the new luxury taste for shark fin soup.

Success underwater depends mostly on how you conduct yourself. Diving can be the most relaxing experience in the world. Your weight seems to disappear. Space travel will be available only to a few individuals for some time, but the oceans are available to almost everyone - now.

People ask: Why should I care about the ocean? Because the ocean is the cornerstone of earth's life support system, it shapes climate and weather. It holds most of life on earth. 97% of earth's water is there. It's the blue heart of the planet - we should take care of our heart. It's what makes life possible for us. We still have a really good chance to make things better than they are. They won't get better unless we take the action and inspire others to do the same thing. No one is without power. Everybody has the capacity to do something.

Like a shipwreck or a jetty, almost anything that forms a structure in the ocean, whether it is natural or artificial over time, collects life.