It was a sunny morning, and the garden smelled of freshly cut grass. A gentle breeze made the leaves dance, and the sky was bluer than ever. Ziggy, Lily, Skye, and Dash had found a little bottle of bubble soap with a straw, and they started blowing bubbles.

"Look at mine, it's as big as a ball!" laughed Ziggy, jumping up to catch it.

"Mine flies higher than all of them," said Lily, stubbornly, blowing with all the breath in her lungs.

Dash ran back and forth across the lawn, trying to pop the bubbles with one finger. Every time, he tripped on the grass and rolled over, laughing his head off.

Skye, on the other hand, blew small, delicate bubbles, and watched them rise into the sky with wide-open eyes. She loved it when the sun shone inside them and painted them a thousand colors.

"They look like flying rainbows," she whispered, with a sweet smile.

Just then, from behind the hedge, came a familiar sound.

"CHOO CHOO!"

It was Toby the Magic Train, with his white puffs of smoke and his cheerful face. The four children ran toward him, clapping their hands and shouting with joy.

Toby blew his whistle and said:

"Hello, dear children, what a bright, sunny day,
a salty adventure is heading your way!
Down under the waves, in the dark of the deep,
one gentle heart wakes the colors from sleep."

"A salty adventure?" asked Dash, scratching his head. "Then we're going to the sea!"

"And something that sleeps..." added Skye, curious. "I wonder what that means."

Without waiting any longer, they all climbed aboard the colorful cars. Toby set off puffing, crossed a field of daisies, rode over a little wooden bridge, and then, with a soft hop, headed straight for the sea.

But the children didn't get wet. As soon as the little train touched the waves, a great clear bubble of air puffed up around them, just like the soap ones, but giant. Inside that bubble, they sank deeper and deeper, into the depths of the sea.

"We're going underwater!" shouted Lily, her eyes sparkling with wonder.

Silvery fish swam past the bubble, and long seaweeds waved as they swayed. But the deeper they went, the more the children noticed something strange.

When the bubble settled on the sand at the bottom, everyone's mouths fell open. But not from wonder: from shock.

The bottom of the sea was all grey. The corals, the plants, the fish, the shells: everything looked switched off, like an old, faded drawing. There wasn't a single color.

"How sad," said Skye, in a tiny voice. "It's as if the sea has fallen asleep."

"Welcome to the Seabed of Sleeping Colors," said a little grey crab passing by, dragging his legs. "It used to be the most colorful place in the sea. Now, look... all grey."

"But what happened?" asked Ziggy.

"Nobody knows," sighed the crab. "The colors fell asleep, and they just won't wake up."

The children decided to find out why. The great bubble rolled slowly over the sand, carrying them around the grey seabed. They looked behind the rocks, among the tired seaweeds, and inside the empty shells.

And then, at the very bottom of everything, where the water grew darker and no sunbeam could reach, they saw a tiny blue glow flickering, weak, like a candle about to go out.

They came closer, carefully. It was a jellyfish. Tiny, see-through, with a little blue light inside that glowed and faded, more and more tired.

"Who... who are you?" asked the jellyfish, in a tiny shy voice. "I'm Lumina. I used to be phosphorescent. But now I can barely do it anymore."

"Phospho... what?" asked Ziggy, tilting his head to one side.

"Phosphorescent," Lumina repeated. "It means I shine with my own light, all my own, just like fireflies do in the night. I was the one who kept all the colors of the seabed glowing."

"So you're the light of the sea!" said Lily, amazed.

Lumina lowered her tentacles, sad. "But I have a secret. I make light... and yet I'm afraid of the dark. And down here it's always so dark. I was so scared, all alone, and my light grew smaller and smaller. No one ever told me that my light was good for anything. So, little by little, I stopped shining. And without me, all the colors fell asleep."

Skye felt a lump in her throat. She knew exactly what it meant to be afraid of the dark.

But just then, a big fish rushed past, stirring up a strong wave. Lumina got scared and fled, slipping into a dark crack under the rocks, in the deepest, blackest spot of the whole seabed.

"She ran away!" said Dash. "And down there it's too narrow: the big bubble won't fit."

So Toby, who was waiting nearby, whistled gently, and out of his chimney came a tiny bubble of air, just right for one child alone.

The four friends looked at each other. To reach Lumina, someone had to climb into that little bubble and go down alone, to the bottom, into the dark.

Skye felt her heart beat fast. The dark water frightened her. Very much, to tell the truth.

And yet she took a step forward. "I'll go," she said, her voice trembling just a little.

"Are you sure?" asked Ziggy. "It's all dark down there."

"We'll wait right here, we won't move," said Lily, placing a hand on her shoulder.

Skye took a deep breath. "Lumina is alone and scared. I don't want to leave her all alone in the dark."

She climbed into the little bubble, which closed softly around her. She sank slowly toward the dark crack. The deeper she went, the thicker the dark became, and her heart pounded like a drum.

For a moment she thought about turning back. The dark was really so deep. But then, at the very bottom, she saw that little blue light trembling again. And she understood something: Lumina was even more afraid than she was. So she found her courage and went on.

"Hello, Lumina," she whispered, when she was close. "I came back."

The jellyfish was shaking. "I'm too afraid of the dark," she cried. "I can't shine. I just can't."

Skye didn't tell her "you mustn't be afraid." She came closer still, reached out her hand until she touched one of Lumina's tentacles, and held it tight, like a little hand.

"You know," she said in a sweet voice, "I get scared too, sometimes. At night, when it's all dark in my bedroom. But my daddy Andrew comes close to me, holds my hand, and tells me he's right there. And then the dark isn't so scary anymore. Now I'm here with you. I'll hold your hand."

Lumina looked at her with her glistening eyes. "But my light is so small," she whispered. "What good is such a small light?"

Skye smiled, and with all her heart she said:

"Your light is beautiful. Don't let it go out."

It was as if something inside Lumina suddenly woke up. For the first time, someone had told her that her light mattered. For the first time, she truly believed it.

And then Lumina's little blue light began to glow. First with a thread of light, then stronger and stronger, until the dark crack filled with a warm blue brightness.

And something wonderful happened. As soon as Lumina shone, the colors of the seabed began to wake up, one after another, like flowers opening in the morning.

First the coral turned pink like a cheek. Then a row of little fish lit up orange and swam away happily. The seaweeds turned green again and started swaying in the current once more. The starfish turned yellow, the shells purple, the little crabs red as fire.

In just a few moments, the whole Seabed of Sleeping Colors had woken up. It had become a rainbow.

"Look! The colors are back!" shouted Ziggy, Lily, and Dash from the big bubble, clapping their hands and jumping for joy.

Lumina spun happily around Skye, shining like a little blue star that had fallen to the bottom of the sea.

"Thank you," said the jellyfish. "You taught me that my light is good for something. And that I don't have to be afraid to shine."

Skye's eyes were a little watery, but she was smiling like never before. And she realized something beautiful: she wasn't afraid of the dark anymore. She had gone down to the blackest spot in the sea, and right there she had found the brightest thing of all.

Back together in the big bubble, the children waved goodbye to Lumina, who now lit up the whole sea with her blue light. Toby was waiting for them, and he rose slowly toward the surface, then off, toward home, through the fields of daisies.

Before leaving them in the garden, Toby whistled one last time and said:

"Go home now, dear children, with stars in your eyes,
that twinkle up high in the bright evening skies.
You learned, as you dove through the deep and the dark,
that one gentle deed lights the world like a spark."

Skye climbed off the train and ran to hug her daddy Andrew, who was waiting for her on the lawn.

"You know, Daddy," she said, "today I took a dive into the dark. And I discovered that when you help someone with kindness, you light up a little too."

Andrew lifted her into his arms and gave her a kiss on the forehead. "Then you're the brightest little girl in the whole world," he said with a big smile.

And Skye, tired and happy, dozed off in his arms, while outside the sun shone bright and warm.

That day Skye had learned something important: learning really is an adventure. Every day you can discover something new and wonderful: you just need the courage to walk through a little fear to take care of someone. Because kindness, she had seen it with her own eyes, always has a special light of its own.