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.

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.

When I arrived on the planet, there were only two billion. Wildlife was more abundant, we were less so; now the situation is reversed.

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.

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.

The Arctic is an ocean. The southern pole is a continent surrounded by ocean. The North Pole is an ocean, or northern waters. It's an ocean surrounded by land, basically.

Far and away, the greatest threat to the ocean, and thus to ourselves, is ignorance. But we can do something about that.