There is this sweet spot in time when we have an opportunity to stop killing sharks and tunas and swordfish and other wildlife in the sea before it's too late.

Since I began exploring the ocean in the 1950s, 90 percent of the big fish have been stripped away. Tuna, sharks, swordfish, cod, halibut, you name it, the numbers have just collapsed. Also, about half of the coral reefs are gone, globally, from where they were just a few decades ago.

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

With respect to the ocean being the heart of our blue planet: We are often asked, 'How much protection is enough?' We can only answer with another question: How much of your heart is worth protecting?

If you make the choice to just go with the flow, that is a choice to make a difference in a negative way.

Why does evolution matter? There is so much about the evolution of life, the development of life on Earth that should rivet the attention of everyone to understand where we've come from and where we might be going. We need to understand the world around us if we are to succeed as a species on the planet.

There's plenty of water in the universe without life, but nowhere is there life without water.