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.

We have become frighteningly effective at altering nature.

Rather than be afraid of evolution and try to stifle inquiry, people should revel in the joys of knowing and find a serenity and a joy in being a part the rest of life on Earth. Not apart from it, but a part of it.

Even if you never have the chance to see or touch the ocean, the ocean touches you with every breath you take, every drop of water you drink, every bite you consume. Everyone, everywhere is inextricably connected to and utterly dependent upon the existence of the sea.

Look at the bark of a redwood, and you see moss. If you peer beneath the bits and pieces of the moss, you'll see toads, small insects, a whole host of life that prospers in that miniature environment. A lumberman will look at a forest and see so many board feet of lumber. I see a living city.

Humans have always wondered the big questions, "Who am I? Where have I come from? Where am I going?" It's part of human nature. It's perhaps the underpinnings of religion.

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.