Delma was enjoying her early morning swim around the vast lake in D'Land just as the sun was peeking out from the horizon casting a warm, golden glow over the glistening water. The water was refreshingly cool in the balmy summer months, especially at this time of the day.

Because of the summer vacations, Delma now had more time to spend around the lake to exercise—something she relished doing.

She was finishing her last lap when she shook her big head, splattering water droplets around her. Her gaze fell on a large, black pool of water at the western end of the lake.

Delma gasped in horror, "Oh dear! What happened to make this side of the lake so dark and murky?"

She paddled closer to confirm that the water was actually inky black.

Delma dunked her head underwater to take a closer look at what could be causing this contamination. "Has someone been throwing stuff in the lake water?" she pondered anxiously. "It can't be just muddy because the water's black, not brown."

At a loss, Delma sped towards the Aquatic School to look for Oily the octopus, their school principal. He was the only one she could think of to help get to the bottom of this mystery.

Olly was painting one of the rocky walls of the coves of the Aquatic School. "Ah! There you are, Delma. I was waiting for you at breakfast," the octopus said as he heard Delma approach.

"Sir," the dolphin said winded and gasping for breath. "The lake...someone's been dirtying it. I saw an entire area of ink-black water."

Olly was startled, "Take me to the place," he said in alarm, discarding his paint supplies.

The two creatures swam speedily towards the western end of the lake. When they finally reached the spot, Delma gasped. The lake water was crystal clear. There was not a drop of black. Delma blinked again. Had she been hallucinating?

Olly looked at her dubiously. "Is this the place, Delma?"

"B...but I am certain that I saw a whole pool of black water; it wasn't just a puddle," Delma stammered.

Olly and Delma spent the next hour diving underwater and investigating the cause of such pollution. When their search ended in vain Oily said calmly, "We can look into it later. Let's go back to school and resume our painting project." Even though Delma spent the entire day helping 011y paint the coves with patterns of seaweeds, her mind kept flitting to the sight of the black water she had seen.

"I'm sure I didn't imagine it," she told her best friends Dazel and Din Din when they met her that evening at the lakeside.

"Let's go and take a look again. We can investigate the surrounding areas," Dazel suggested. "I love a good mystery."

"I'm sorry I can't accompany you all. It'll be sundown soon and I have to be home for a family dinner. It's my Grandparents' anniversary!" Din Din said ruefully, excusing himself.

So, it was Dazel who flew towards the western end of the lake while Delma cut like a flash through the water. When they reached the western end, there was nothing out of the ordinary. The water was crystal clear again.

"Let's talk to a few creatures which live in this area," Dazel recommended. But it was strange that they couldn't encounter any creatures. "That is strange! I remember a lot of fish used to live at this end of the lake."

"Could the black water have killed them?" asked Delma aghast.

"But if that was the case we would have seen their bodies," Dazel dismissed the option shaking her head.

The sun had set and they couldn't continue their search. "Maybe we can return tomorrow morning," Delma said. "I was swimming in this vicinity just as the sun was rising when I saw the black pool."

"I'll be here before dawn," Dazel promised.

Before bed, Delma encountered Dell the mischievous beaver who was lazing on a rock at midnight and asked him.

"Do you have any idea about which creatures lived at the western end of the lake?"

"The shoal of angel fish who lived there have moved to another part of the lake," Dell said thoughtfully as he chewed on a straw.

"Do you know why?" inquired Delma.

"There was some talk of some other creatures moving into that area of the lake. The new inhabitants had some strange habits, I believe," Dell shrugged nonchalantly.

Delma tossed and turned all night with images of black, murky water giving her nightmares. When she awoke for her morning swim, she was more exhausted as compared to when she had fallen asleep. "Come on, Delma," came an annoyingly cheerful quack.

It was Dazel perched on a rock. Delma grimaced. Dazel seemed to have slept well. Determined to get to the bottom of the black water mystery the two friends revisited the western side of the lake.

"Look! The water's black again," Delma said triumphantly pointing towards the pool of ink.

Dazel seemed fascinated.

Delma dove under the water. The entire depth of the water was cloudy. Suddenly, Delma saw a group of strange eight-armed creatures fly out of the water. She came to the surface.

"Did you see that?" she yelled to Dazel.

"Yes, they had arms and two long tentacles and a very strange pen-like body," Dazel shouted.

"They are squid," came a voice from the water's edge. It was 011y the octopus and he was grinning. "Come with me and I'll explain," he gestured with his tentacles.

"Squids are cephalopods and usually live right at the bottom of the lake or sea bed where they can't be disturbed," said Olly.

"They seemed to have moved to this part of the lake a few weeks ago. The angel fish who lived here apparently left the area because the squids were squirting ink. I found this out today when I went to pay a visit to the angel fish."

"Why and how do they squirt ink?" asked Delma.

"They do it when they feel they are being threatened by some other creature." said Olly.

"Can we meet the squid?" asked Dazel hopefully.

"They really don't like to be bothered," Olly replied, "But we will have to warn them not to unnecessarily contaminate our lake water."

"What a relief!" sighed Delma. "I'm glad we unraveled this mystery. I couldn't have endured another sleepless nightmarish night."

And Olly and Dazel laughed.