Fortunately, we know more about the problems that we have than in all preceding history. We know now the consequences of the things that we put into the air, into the water - of the way we treat life on Earth.

I've spent thousands of hours under water. And even in the deepest dive I have ever made, 2.5 miles (about 4 kilometers) down, I saw trash and other tangible evidence of our presence.

The diversity of life on Earth, generally, is astonishing. But despite those large numbers, it's also important to recognize that every species, one way or another, is vulnerable to extinction. And in our time on Earth... our impact on the diversity of life has been profound.

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.

Sharks are beautiful animals, and if you're lucky enough to see lots of them, that means that you're in a healthy ocean. You should be afraid if you are in the ocean and don't see sharks.

Since the middle of the 20th century, more has been learnt about the ocean than during all preceding human history; at the same time, more has been lost.

I suggest to everyone: Look in the mirror. Ask yourself: Who are you? What are your talents? Use them, and do what you love.