Below, the whale sang on, the boat vibrated with each note. The stainless rail at the bow began to buzz. Nate could feel the deeper notes resonate in his rib cage. The whale was into a section of the song they called the «green» themes, a long series of whoops that sounded like an ambulance driving through pudding. A less trained listener might have thought that the whale was rejoicing, celebrating, shouting howdy to the world to let everyone and everything know that he was alive and feeling good, but Nate was a trained listener, perhaps the most trained listener in the world, and to his expert ears the whale was saying — Well, he had no idea what in the hell the whale was saying, did he? That's why they were out there floating in that sapphire channel off Maui in a small speedboat, sloshing their breakfasts around at seven in the morning: No one knew why the humpbacks sang. Nate had been listening to them, observing them, photographing them, and poking them with sticks for twenty-five years, and he still had no idea why, exactly, they sang.

"He's into his ribbits," Amy said, identifying a section of the whale's song that usually came right before the animal was about to surface. The scientific term for this noise was «ribbits» because that's what they sounded like. Science can be simple.

Nate peeked over the side and looked at the whale that was suspended head down in the water about fifty feet below them. His flukes and pectoral fins were white and described a crystal-blue chevron in the deep blue water. So still was the great beast that he might have been floating in space, the last beacon of some long-dead space-traveling race — except that he was making croaky noises that would have sounded more appropriate coming out of a two-inch tree frog than the archaic remnant of a superrace. Nate smiled. He liked ribbits. The whale flicked his tail once and shot out of Nate's field of vision. "He's coming up," Nate said.