As Rio leaned forward, he couldn’t help but let out a gasp. Because illuminated in the whale’s heart-shaped breath was the most beautiful sight he had ever seen.

“A rainbow?”

“Not just a rainbow,” Marina whispered. “A rainbow heart.”

Glistening and shining, as if the heart were made of magic. The best kind of magic.

“It’s the oil in their breath catching the sun’s rays,” she explained.

Around him the cameras clicked and whirred, but Rio was frozen to the spot. He couldn’t describe the feeling that coursed through his body. It was nothing he had ever felt before. Nothing like being at the zoo, where there was a wall or a fence between him and the animals. This was complete wilderness. Something pure and untouched and free.

His mind flashed back to the photo of his mom on the boat. The joy on her face and the light in her eyes. No wonder! It was at this precise moment that Rio finally understood why she had loved the whales so much. Because who couldn’t fail to love an animal that made rainbows?

“It’s swimming away,” Marina said. “Check out the tail.”

Through the binoculars, Rio watched as the huge tail flicked once, then twice, before slipping back into the water and disappearing. Only after the whale had gone did Rio wonder if it could have been White Beak. It had been impossible to tell. In fact, everything had happened so quickly, he’d not even taken any photos.

Just as he was cursing himself for being so slow, Rio heard something.

Not the thwack-thwack of the waves or the click-click of the cameras or even the cry of the gulls or the excited chatter of the humans. But something else entirely. An echo rising up from the depths. A strange rumbling, groaning noise he had never heard before.

“That noise . . .”

“What noise?” Marina said, turning to him. “The water slapping against the hull?”

“No. Not that. The other noise.”

“The other noise?” Marina looked puzzled. “You mean the engine?”

Rio shook his head and tried to listen. But whatever it was had gone. Disappeared into the depths. He settled himself back down and lay with his fingers trailing above the water. As Marina filled in her notebook, he felt a sense of relaxation drift over him. How strange that he didn’t feel self-conscious, or shy or anxious or any of the things he tended to experience on land. He felt—and this sounded a bit silly even to his own ears as it was only his first-ever boat ride—almost at home.

Even if he didn’t get to see White Beak today, just knowing she was close by, it gave Rio a curious sense of comfort. As if his mother was here with him. That he could almost hear her voice whispering to him across the ocean.

But just then . . . the sound was so vivid that he sat up. He wasn’t imagining things. He could hear something. The same echoey noise he’d heard just moments earlier. Rio looked around. Marina was still making notes about the whale they’d just seen, while Birch was describing migratory behavior to the others.