He stood at the bow of the ship, discouraged, and gazed down into the churning green water. He felt a sudden, strong urge to go for a swim. This time, he did not suppress it.

He hit the water with incredible force. The current was strong and shockingly cold, and it pulled him down.

He did not fight it. He felt himself drowning.

From out of the darkness emerged a giant eye suspended in a wall of gray flesh. It was a whale, and it was moving toward him rapidly. Before it could collide with him, the whale dove and disappeared from view. Then, just as suddenly, Zheng’s feet connected with something solid. The whale was pushing from below, propelling him upward.

They broke the surface together. Zheng coughed up a lungful of water. Someone from the ship threw him a rope. He tied it around his waist, and as he was being pulled back on board, he heard the whale singing below him.

Its song said: follow me.

As he was pulled onto the deck, Zheng saw the whale swim away. Though he was trembling from cold and struggling for breath, he found the strength to shout, “Follow that whale!”

The Improbable trimmed its sails and gave chase. They followed the whale all that day and through the night, marking its position by the mist from its blowhole. When the sun rose, there was an island on the horizon—one that did not appear on the map.

It could only be Cocobolo.

They sailed toward it as fast as the wind would take them, and throughout the day what had been a mere speck on the horizon grew larger and larger. But night fell before they could reach it, and when the sun rose again the island was but a speck in the distance.

“It’s just as they said,” Zheng marveled. “It moves.”

They chased the island for three days. Each day they drew tantalizingly close to it, only for it to slip away each night. Then a strong wind pushed them toward the island faster than ever, and finally the Improbable was able to reach it, anchoring in a sandy cove just as the sun was dipping toward the horizon.

Zheng had been dreaming of Cocobolo for months, and he’d let his dreams run a bit wild. Reality was nothing like what he’d envisioned: there were no waterfalls of gold pouring into the sea, no mountain slopes glimmering with ruby-laden trees. It was a lumpy collection of unremarkable hills covered with dense greenery, exactly like a thousand islands he’d passed in his travels. Most disappointingly, there was no sign of his father’s expedition. He’d imagined finding his ship half sunk in a cove, and the old man himself, twenty years a castaway, waiting for him on a beach, cure in hand. But there was only a crescent of white sand and a wall of waving palm trees.

The ship dropped anchor, and Zheng splashed ashore with his first mate and a detachment of armed crewmen. He told himself it was too soon to be disappointed, but after several hours of searching they had found neither Liu Zhi nor any sign of human settlement, and Zheng was more disappointed than ever.