The bubbles came up at six in the morning, which is the hour on Crownstone Island when the cooks are still arguing about porridge and the gulls have not yet committed to a plan. There were four of them at first. Then nine. Then a slow steady chain, fat and gold-tinted, breaking the surface of the Glitterdeep just past the end of Bananapeel Bay's longest dock. They caught the early light like tiny rising suns and made a sound that wasn't quite a sound. More of a soft tock, the way a wooden spoon taps the inside of a bowl.

King Ted, who is seven years old and rules an island roughly the shape of a slightly bitten biscuit, saw them from the dock because he was already on the dock. He had been on the dock since five forty-five. He had told nobody where he was going, which is something he does most mornings, and which his subjects have learned to factor in.

He was wearing the crown. Not the gold one. The gold one lives in a velvet box in the throne room and is, in Ted's private opinion, heavier than a king's head can really be expected to bear. He was wearing the paper one. It had been folded out of a single sheet of butcher paper three months ago and was now soft as a handkerchief at the corners, crumpled into a kind of permanent lean, and covered in crayon. There was a drawing of a whale on the front. There was a drawing of a coconut on the side. There was a small purple smudge that had once been a drawing of Bellyroo and was now, charitably, a drawing of weather. Ted saw the bubbles and went very still, which for him takes effort.

Then he turned around and shouted down the dock at the top of his small, considerable lungs. "BELLYROO. BELLYROO. BELLYROO IT IS HAPPENING." Bellyroo had been halfway up the path from the kitchens carrying a basket. Bellyroo is twelve, which on Crownstone Island makes her practically a grown person, and she has the kind of patience that comes from being slightly taller than everyone she loves. The basket contained two flatbreads, a wedge of yellow cheese, six small pickled things, and a flask of water with a slice of lime in it. She had been planning on a quiet day. She had planned the quiet day yesterday. She had told the cook about it. She had told herself about it twice. She came down the dock at a walk, because Bellyroo does not run when she can arrive.

"Now, I'm not saying we shouldn't be excited," she said, kneeling beside Ted, "but what exactly is happening." Ted pointed. The bubbles tocked. Bellyroo looked. She closed one eye, the way she does when she's thinking, and watched a fresh cluster come up. They were not the color bubbles usually are. They were the color of a coin that had been polished by somebody who really cared. "Hm," she said. "Hm is not enough," said Ted. "Hm is for porridge. This is the Glitterdeep doing something. Bellyroo. The Glitterdeep is doing something." "It does do things," said Bellyroo, gently. "That's mostly what it does." "Yes but," said Ted, and then he ran out of words for a second, which is rare, and used the gap to drop to his knees on the dock planks and press his nose almost to the water.

The wood smelled like salt and old rope. The water smelled like nothing he could name. He stared straight down into the green, past his own reflection, past the wobble of his paper crown bent backwards, past the small brown crabs going about their crab business on the pilings. Down, down, into where the light gave up. And something, very far below, glimmered back. It was the smallest glimmer. A flicker. The kind of thing you could blink and lose. It was gold, or it was not gold, or it was the idea of gold thinking about itself. It happened once. Then it didn't happen again. Ted sat up very slowly. His eyes were enormous. "Bellyroo." "I saw it," said Bellyroo, who had not seen it, but who had seen Ted's face and knew which was the more reliable instrument.

"That," said Ted, "is the Hoard. That is the Glitterdeep Hoard. That is the actual real true Hoard from the stories. The one with the. The one that the old fishermen sing about when they think no one's listening. The one with the chests and the. AHA!" He stood up so fast the dock made a noise. "Right! Here is what we do. We get the Regal Peel. We get supplies. We get me a slightly bigger hat for at sea, this one is for shore, and we sail out before the bubbles stop because Bellyroo, Bellyroo listen, what if they stop." Bellyroo did not answer immediately. She was looking at the basket in her hand, and at the line of small pickled things, and at the quiet day she had planned, which was already, she could feel, walking away from her down the beach.

"Now, I'm not saying we shouldn't," she said carefully. "But the tide turns at noon. And we don't actually know what the bubbles are. They could be a fish. They could be a hot spring. They could be a very confused octopus." "They could," said Ted, who was now pacing, "be all three." "That isn't reassuring." "It isn't meant to be reassuring. It's meant to be interesting." Bellyroo set the basket down on the planks. She looked at the bubbles. She looked at Ted. She looked at the bubbles again. A small breeze came up off the water and lifted the corner of the paper crown. "A king," she said, mostly to herself, "who doesn't go and look is just a person in a chair." Ted swung around. "Who said that." "I did. Just now." "It's good. Write it down." "I won't."

Down the beach, in the wet sand where the tide had pulled back, a single shape had been pressed into the shore overnight by something the night hadn't bothered to explain. Two curved lines, hinged. A little like a claw. The gulls walked around it without stepping on it, which is not normal gull behavior, but no one was watching the gulls. Ted was at the end of the dock now, one hand clamped to the paper crown to keep the wind from taking it, the other arm pointing dead straight out at the horizon as if he could pull the horizon closer by sheer royal will. The crown had blown sideways and was hanging off his left ear at an angle no crown has ever been designed for. He did not appear to notice. He looked, in that moment, exactly like a king.

Behind him, without comment, Bellyroo picked up the basket, turned back toward the kitchens, and began, quietly, to pack a second lunch.

The workshop door didn't open so much as surrender. The wind took it, slammed it flat against the courtyard wall, and out came the contents in the order they had been stacked: a coil of copper piping, a length of rubber tubing the color of an old bruise, a wooden crate labeled ABSOLUTELY NOT BANANAS, and three monkeys. Two of them landed on their feet. The third, Wobble, landed on the crate, which made a noise like a kazoo apologizing. Nip and Tuck swore in unison. It was a small swear, the kind you'd use in front of an aunt, but it was perfectly synchronized, and Bellyroo, watching from the courtyard arch, raised an eyebrow at the precision of it. King Ted pressed his paper crown flat against the wind and crossed the cobblestones at a trot.

"Royal Inventor Wobble," he announced, "I, King Ted, hereby proclamate, proclamationate, I'm calling you up. For sea duty. There's bubbles. We're going." Wobble did not get off the crate. He held up one long finger, which was a thing he did when he wanted the world to wait. "A simple matter of timing, Your Highness. The pneumatic descender is at ninety-one percent. I do not sail at ninety-one percent. My associates do not sail at ninety-one percent." Nip and Tuck, who would sail at any percent Wobble told them to, said nothing. "How long's nine percent?" Ted asked. "Two days." "We have an hour." "Then we have a problem," said Wobble, "which is, obviously, my favorite kind of thing."

The western sky was the color of a wet slate roof. Out past the harbor wall the water had gone from blue to the particular gray that means the sea is thinking about its options. A gull went the wrong way overhead, fast. Bellyroo stepped forward. She hummed, three notes, low to high to middle, and closed one eye. Then she reached into the pouch and produced a small brass clamp, the kind with a wing nut on top. Wobble looked at it. Wobble looked at her. Wobble looked back at the clamp. "I was about to ask for that." "There we are," said Bellyroo. "Now, I'm not saying we shouldn't wait," she added, gently, to Ted, "but the harbor master just took down the green flag. He's holding the yellow one. He hasn't put it up yet. He's deciding."

Ted looked. The harbor master, a distant figure in a distant coat, was indeed holding a yellow flag at waist height, like a man weighing fruit. "Wobble," Ted said. "Bring the ninety-one percent. We'll be the other nine on the way." Wobble opened his mouth to argue. Then he closed it, which was rare enough that Nip and Tuck exchanged a glance. He hopped off the crate. "Associates," he said. "Load order. Pipes, tubes, crate, the other crate, the crate we don't talk about, my hat. Move." They moved. They moved like they'd been waiting their whole lives for someone to say load order, which, in a sense, they had.

The Regal Peel sat at the long dock with her yellow hull bright against the darkening water. She was not a large ship. She was an enthusiastic ship. Her sail was the color of a ripe banana and her name was painted twice, once on each side, because Ted had insisted that ships, like kings, should be recognizable from any angle. By the time the first raindrop hit, Wobble had a blueprint unrolled across the foredeck and was anchoring its corners with whatever was to hand: a mug, a coil of rope, a boot that may or may not have been his. The paper was the color of weak tea, hand-inked, and absolutely enormous. The raindrop landed in the middle of it with a sound like a knuckle on a table.

Bellyroo, leaning in with a tray of warm root-vegetable drink in clay cups, paused. Her eyes had caught on something in the corner of the diagram, half-tucked under the mug. A small shape, inked in fine line. A crab claw, open, with a hinge drawn in. Beside it, a number, and beside the number, a question mark in Wobble's spiky hand. She did not say anything. She set down the tray. She moved the mug a quarter inch and looked again. Wobble, busy elsewhere on the page, didn't notice. "Cast off forward," called the bosun, who was a goat named Phyllis, but that's another story. The rope at the forward cleat slipped its loop. The Regal Peel, freed, took one slow breath toward open water. The first real wave came up under her bow and lifted, and the dock began, very gently, to be somewhere else.

Ted climbed to the prow. The wind took at his paper crown and he pressed it flat with the heel of his hand, the way he had started doing without thinking about it, the way a person presses a hat they've owned a long time. He didn't turn around. Behind him, Rumblefort shrank, the courtyard with its scattered copper piping, the harbor master lowering the yellow flag, the workshop door still swinging on its hinge. Ahead, the sea was deciding what kind of afternoon to be. Ted watched it decide.

The water above the bubble site was the wrong color for water. Not blue, not green, but somewhere between a bottle and a leaf, and humming faintly, the way a held note hums in the chest after the singing stops. Ted leaned over the rail of the Regal Peel and watched the column rise. The bubbles came up in a steady stream, one every second, give or take, and each one popped at the surface with a small sound like one person clapping from very far away. "It's applauding us," Ted said. He pressed his paper crown flat against the breeze. "Bellyroo. The sea is applauding us. Is that normal? Has the sea ever done that before? Wobble, write it down."

"My associates are already documenting," Wobble said, from somewhere near the winch. He was not, in fact, documenting. He was tightening a brass screw with great seriousness, the kind of seriousness people perform when they have never tightened that particular screw before but intend the outcome anyway. "A simple matter of pressure differential, obviously. The cavern below is exhaling. Like a very polite whale, or a banana left in the sun." Nip and Tuck nodded in unison without looking up. Bellyroo said nothing. She was already at the diving bell, checking the seal with two fingers, humming her three-note hum. She had been humming it for most of the morning. It is worth knowing, about Bellyroo, that she hums when she is thinking and she hums when she is worried, and only she can tell the difference.

"You're sure," Ted said. He had walked over without seeming to decide to. "You're sure you should be the one to go." "I'm sure I shouldn't ask you to," Bellyroo said. "Not the first time." Ted opened his mouth. Closed it. He had a royal proclamation half-formed about the duties of kings and the leading from the front of things, but he caught Bellyroo's eye and the proclamation went back wherever proclamations go to wait. He nodded instead. He pressed his crown flat again, although the wind had stopped. "By order of me," he said quietly, "come back up." "By order of you," Bellyroo agreed. The bell went down with a sound like a kettle being lowered into a well. Wobble worked the winch with both hands and a great many opinions. Ted stood at the rail and watched the rope go and go and go.

What Bellyroo saw, when the bell reached the cavern mouth, was not what the legends had promised. The legends had promised gold. This was better and stranger than gold. The cavern was lit from the inside, soft and slow, by a thousand small lights that were not lights but bubbles, clinging to the rock in clusters, drifting loose, rising in their slow steady column toward the surface. The walls were pale and ridged and the light moved across them like the inside of a shell held up to a lamp. She stepped out of the bell. The water held her gently. Her three-note hum carried oddly through the helmet, flattened and warm. She reached into the pouch.

She didn't know, before her hand was inside it, what the pouch would give her. She rarely did. Today it gave her a glass vial, no bigger than her thumb, with a tiny cork already half-turned in its neck. Then another. Then another. Three. She held the first vial up to a bubble the size of a plum and let it drift inside. She sealed the cork. The cavern dimmed. Not a lot. One shade. The way a room dims when a single candle is taken out of it. Bellyroo went very still inside her helmet. She hummed her three notes. She listened to the cavern listening back. She captured the second bubble. The cavern dimmed again, the same exact shade, as if it were keeping careful accounts.

She set the two sealed vials on a flat shelf of rock and stood looking at them for a long moment before she captured the third. There was a question in this, and she was trying to ask it carefully. The hoard, it turned out, could be taken. It just preferred you noticed that you were taking it. She sealed the third vial. She set it beside the others. Three small glass thumbs of gold light on a gray shelf, and the cavern around them one full shade darker than when she had arrived. That was when she felt it.

Not saw. Felt. The way you feel a person come into a room behind you. Somewhere past the cavern mouth, out where the water turned from green to nothing, something was moving. Slowly. Without hurry. The kind of without hurry that belongs to a thing that has never needed to hurry. Bellyroo gathered the three vials into her arms. She turned, very carefully, toward the bell. Behind her, through the cavern mouth, in the dark water beyond the last of the light, a shape slid past. Long. Unhurried. She caught the curve of it and then she caught only water, and then the water was only water again. She did not hum. She tugged the rope twice, which was the signal for up, and then a third time, which was not a signal they had agreed on but which Wobble, above, understood immediately and without comment.

On deck, Ted took the three vials from her gloved hands one by one. He held them up against the late afternoon and they each gave back a soft gold light, steady, patient, as if they had not yet decided what they were. "What did you see?" Ted asked. Bellyroo looked at him. Then past him, toward the dark line of the horizon where the green water turned ordinary again. "We should go forward," she said. "But not tonight." Ted nodded slowly. He did not ask again. That, more than anything, is the thing to notice about him this afternoon: he did not ask again.

He carried the three vials down to his cabin himself, one at a time, and set them in a row on the small shelf above his bunk. They glowed faintly through the evening. They were still glowing when he fell asleep with his paper crown beside him on the pillow, and they were still glowing, very faintly, when something very large and very far below the Regal Peel turned, in its own time, and began to drift after the ship.