Camila had visited the bay near her grandmother’s house in Puerto Rico many times, but always during the day. Tonight was different. Her cousin Diego had promised her a surprise, and they were going out in a kayak after dark.

There was no moon. The water looked black and still. Camila held her paddle tightly. “What exactly are we looking for?” she whispered.

“Dip your paddle in the water,” said Diego, grinning.

Camila pushed the paddle into the bay. Suddenly the water around it flashed with blue-green light, as if someone had scattered thousands of tiny stars. She gasped and lifted the paddle out. Glowing drops fell from it like sparkling rain.

“Is it magic?” she asked.

“It’s even better,” said Diego. “It’s science. The water is full of tiny living things called plankton, much too small to see. When the water moves, they give off light. This is called bioluminescence.”

Camila trailed her fingers in the water, and five glowing lines followed them. A fish darted beneath the kayak, leaving a shining path behind it.

“Why do they glow?” she asked.

“Scientists think the flash might scare away animals that want to eat them,” said Diego. “Like a sudden alarm.”

On the way back to the shore, Camila was quiet. She kept thinking about how something so tiny could make such a beautiful light.

At breakfast the next morning, she drew a picture of the glowing paddle. Underneath, she wrote: “Small things can shine too.”