The water was freezing. And unlike what Cecily had promised, it was dark. So dark that Barclay couldn’t see, and the deeper they descended into the blackness, the more panic clawed up Barclay’s throat. He squeezed his eyes shut and pressed his forehead against Mar-Mar’s slippery back, and he didn’t dare even to breathe.

“Whoa!” came a voice ahead of him—one of the girls.

“It’s beautiful!” said another.

“I’ve never seen anything like it!” That voice was Viola’s.

Finally, Barclay peeled his eyes open. All around them, blue speckles glimmered, as though Mar-Mar was surrounded by floating starlight. They must’ve been Firenekkies, which Hasu claimed lit the Munsey streetlamps. Their glow made it bright enough to spot the river below, which truly did look like a current winding across the ocean floor. Its sludgy water reminded Barclay of a mudslide.

The Sea was also growing warmer than he’d expected, and the farther they dove, the warmer it became. Then he spotted the source of the heat. Clustered around the edges of the river were vents, spewing up smoke and streams of bubbles. It was so warm that Barclay’s skin flushed pink.

“Hasu and I will get off here,” Viola said, her voice sounding muffled and distant through the water. “The rest of you keep going.”

She and Hasu climbed off and floated at the edge of the river. Then Cecily grabbed two of the black marbles from her pocket. She tossed them, and the marbles popped! Out sprang a pair of Sunboards. If the Beasts had been surprised to be held as shadow prisoners, they didn’t show it. They drifted upside down, eyes blank, their mouths bobbing open and shut.

Mar-Mar took off again, following the riverbank until they’d traveled far enough to satisfy Cecily.

“This little bend looks like it’s a third of the way, from the map,” Cecily said. She handed her map to Shazi and two of the shadow marbles to Tadg. “Swim down until you reach the lumpy lichen rock—that marks the last third. Just give the marbles a toss when you’re ready. Come on, Barclay!”

Barclay climbed off. He still thought this plan was a bad idea, but he had to admit—it was amazing down here. While on the surface, all Barclay could see of the Sea was endless dark water, but underneath, it was beautiful. Countless strange plants sprouted along the ocean floor, seaweed bushes and nettles and colorful blooming flowers. Tiny Beasts swam among them. There were whole schools of fish that vanished and reappeared at random. Crustaceans drilled tunnels into the sand. Crowded around the vents, the Firenekkies glowed like aquatic lightning bugs.

“It’s incredible, isn’t it?” Cecily said. Then she stretched her muscles, preparing for the race. “But I won’t be distracted. My Lore might be no good down here, but I’m not taking it easy on you.”