I actually love diving at night; you see a lot of fish then that you don't see in the daytime.

We humans have this idea that the ocean is so big, so vast, so resilient that it doesn't matter what we do to it. That may have been true 1,000 years ago. But in the last 100, especially the last 50 years, we have destroyed the assets that make our lives possible.

This is a living planet. Look around. Mars, Venus, Jupiter. Look beyond our solar system. Where else is there a place that works, that is just right for the likes of us? It has not happened just instantly. It is vulnerable to our actions. But it's the result of four and a half billion years of evolution, of change over time. And it changes every day, all the time. It would be in our interest to try to maintain a certain level of stability that has enabled us to prosper, to not wreck the very systems that give us life.

I am driven by what I know; that the world I love is in trouble.

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.

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.