David Doubilet: The greatest underwater photo ever made is not an underwater photo. It was made by astronaut William Anders on Christmas Eve 1968 — one of the most terrible years in our history — but in one split second, one of the most momentous, important images ever made. He pointed his camera out of the little tiny window of Apollo 8 as it was coming around the dark side of the moon. And there in the foreground was the moon. Everybody’s seen this picture. And in the background is the earth rising, as it were, against the absolute black velvet of space. It’s not a blue marble, but it’s a sapphire. And this picture says one thing to all of us, every single human on the planet. It says, “That’s all there is.” But for me, and a few of my colleagues, like Dr. Sylvia Earle, it says, “This is a water planet.” She says. “This is not Planet Earth, this is Planet Ocean,” and it is 70 percent of its surface, and blue is the color of life found nowhere else in the universe.