In the dark, I received a signal from my companions.

Then, Shen Bing and Lu Zhe started communicating with simple phrases. In this situation, they managed to achieve communication. Both groups were so excited that they couldn't sleep.

After a while, Ning Shu noticed the flickering lights from Lu Zhe's side: "What are they doing?"

"Don't know," Lin Qianqian thought for a moment, "But it looks a bit like Morse code!"

"So awesome. Do you understand this?"

Lin Qianqian shook her head.

Ning Shu thought for a moment: "Although we don't understand, we can be sure that Lu Zhe and Sister Bing are communicating. We can also use our way!"

As she said that, she shook the flower lantern in her hand.

A lotus lantern floated out from the northern water, emitting a dim glow, slowly drifting towards the center of the ocean.

Lu Zhe saw it. Tang Xiaoguo saw it too!

"Look, a flower lantern!"

"Yeah!" Shen Bing nodded: "It looks like they are also actively responding!"

"I'm bored with nothing to do. I'll make a flower lantern too!"

"Okay, if you want to make one, then..." Shen Bing seemed to have thought of something as she spoke to this point: "You were washed back after jumping into the sea. Can your flower lantern drift into the sea?"

"That's weird. Why can Classmate Qianqian's lantern drift into the water while mine can't? Is this also a matter of luck?"

"Didn't Lu Zhe say there are converging warm and cold currents here? I guess it may be the result of different ocean currents!" Speaking of this, Shen Bing's eyes lit up:

"That's right, we can't release lotus lanterns, but you can make a Kongming lantern. It may help Lu Zhe determine the wind direction! Xiaoguo, can you make this?"

Tang Xiaoguo thought for a moment: "Resin for candle, bamboo sticks for support, plastic bags for canopy. No problem at all!"

...

Half an hour later, Lu Zhe saw the flower lantern start spinning and accelerate four to five hundred meters away from him before eventually sinking into the sea.

A Kongming lantern rose from the south but slowly drifted northeast.

Lu Zhe didn't continue sending Morse code, but fell into deep thought.

"What's wrong, Lu Zhe?"

"Did you notice the spot where the flower lantern was sucked in by the whirlpool?"

Jiang Yao nodded: "It seems to be a few hundred meters closer to us than before."

Lu Zhe nodded: "That's right!"

Jiang Yao said in horror: "Could it be following us?"

Lu Zhe thought for a while: "When I took Classmate Shen and Qianqian to the other side of the stone forest, although there were undercurrents, I didn't feel such strong suction. But when I took you there, the suction was very strong. What does this mean?"

Jiang Yao thought for a while: "It thinks we look good?"

Lu Zhe shook his head: "This means the whirlpool is indeed moving. But it's not that realistic to say it's following us... Or perhaps, that's not one whirlpool."

"There are several?"

Lu Zhe pondered and came up with his own hypothesis: "Possibly countless ones!"

"Ah? That's too exaggerated!"

"It's actually not scary or exaggerated at all. Many small whirlpools can easily form at the confluence of two ocean currents. They are very weak at the beginning, but as they move along the confluence line of the two currents, they will absorb more and more energy and become bigger and bigger until the whirlpool encounters a volcanic island and disappears. So, the whirlpool that threatened us before and the one that sucked in the flower lantern now are very likely not the same whirlpool!"

"No wonder there's no sandy beach there. They must have been washed away by the swirling currents."

"That's right."

Jiang Yao thought for a moment, then asked again: "Why is it moving towards us instead of the other direction?"

Lu Zhe looked at the Kongming lantern that was about to disappear into the night sky: "I guess like monsoons, it is affected by the Coriolis force of the Earth's rotation. The whirlpools in July move from southwest to northeast, while those in January move in the opposite direction, from northeast to southwest. Where exactly they will stop is unclear."

"Then...how useful is this knowledge to us?"

"Of course it's very useful. Knowing the movement pattern of the whirlpools, we can find safe intermittent points. Then we can make a raft and reunite with our companions on the volcanic island!"

At 11:30 pm, Shen Bing received the last string of characters from Lu Zhe: "waitforus!"

She understood that Lu Zhe must be trying to find a way to reunite with them. What they needed to do was survive well here and wait for Lu Zhe to come back.