It's June, and the sun is still relatively abundant, so when they were on the boat, the three of them felt a little stuffy in their wetsuits, but when they entered the water, this stuffiness disappeared, especially as the depth increased, and the temperature began to gradually decrease.

Because the heat conductivity of water is much higher than that of air, the loss of heat in the water is also greater than that on land, but fortunately, there is a diving suit to keep out the cold, and this kind of recreational diving generally does not dive too deep, because of the pressure, every 10 meters in the water will increase the pressure of one atmosphere, more than 30 meters will be in danger of drunk nitrogen (ordinary recreational diving cylinders are mainly filled with compressed air, that is, 21% oxygen and 79% nitrogen, high pressure will let nitrogen into the body, Similarly, oxygen breathing at high pressure for too long can also cause oxygen poisoning).

And Zhang Heng and the underwater ruins they went to this time are about 25 meters deep, this depth is basically no danger, with the water nature that Zhang Heng has exercised in the Black Sail Copy, even if he doesn't bring any equipment, he can dive to this depth with just one breath, of course, in that case, he doesn't want to stay down for a long time, basically he has to go back to ventilate when he sees the ruins.

Strictly speaking, this is not Zhang Heng's first diving in Okinawa.

When he was a child, he followed his parents to see coral in Sanya, but it was a pure parent-child leisure, the depth of the dive was less than eight meters, and the time spent underwater was also very short, only 20 minutes, and the whole process was accompanied by an instructor.

If you really want to calculate it, when Zhang Heng stayed underwater for a long time in his equipment or in the Apollo training camp, NASA used the underwater environment to simulate weightlessness, Zhang Heng not only had to stay underwater, but also had to receive instructions from the console there to complete a series of operations.

Therefore, when he returned to the water, Zhang Heng did not feel unfamiliar.

Whether it is the feeling of weightlessness or the quiet underwater, the sea water almost isolates all sounds, and every diver can only hear their own inhalation and exhalation when diving, especially when exhaling, the bubbles pass through the sea water and float upwards, which is quite reassuring.

Nelly was as competent as she said, always staying no more than two meters away from the two of them, closely watching the physical and mental conditions of the two, making sure that they were not in any trouble when they dived, and then gesticulating, pointing to the ruins not far away, and asking the two to follow her.

In fact, there is no need for her to make a special gesture, as long as you dive into the water, it is difficult to ignore the scene in front of you. It is a huge undersea palace or pyramid-shaped structure that looks very dilapidated from the outside, and is said to date back to about 10,000 BC.

If this underwater site was built by the people who lived here at that time, they may have reached the level of the Egyptians at the time of the pyramids, and the latter occurred around the third millennium BC.

This is why many experts firmly believe that the stone building in front of them is just a coincidence of nature, but after witnessing the neat stone steps and smooth and square right-angled rock walls, Han Lu still prefers to believe that this is really the relic left by some mysterious lost civilization.

She even saw traces of what appeared to be gates and roads.

Nelly gestured to let Zhang Heng and Han Lu get closer, while she picked up the underwater camera, helped the two take a photo with the underwater ruins in front of them, and then swam towards the gate.

Han Lu followed closely with the VCR, while Zhang Heng glanced at the time and direction on the dive computer, and then followed.

The three of them passed through the stone gate in turn, saying that it was the city gate, but in fact it was just three pieces of stone put together, during which leisurely tropical fish swam in front of Zhang Heng's eyes from time to time, and Zhang Heng also saw a small sea rabbit.

As the name suggests, this sea creature looks as cute as a rabbit with ears (but it is not excluded that there are ugly sea rabbits, there are many kinds of this thing), from a strong woman like Han Lu to a little girl like Nelly, who can't bear this kind of cute thing and sell cuteness, and shoots around it, just like a photographer under the Victoria's Secret Table.

After a delay of about a minute, the three of them swam through a somewhat narrow area, the narrowest of which was only about two people side by side, and then the view suddenly widened, as if they had come to the hall of this underwater palace.

Look around and see walls made of rocks, and the sparkling water overhead.

Nelle, who was leading the way at the front, stopped, folded her left and right hands together, and quickly swung her thumb up and down, which was to tell the two that there were turtles in front of them to see, Han Lu swam over when she saw this, and sure enough, she saw two turtles between the cracks in the rocks, so she also waved to Zhang Heng behind her, signaling him to hurry up.

But Zhang Heng remained in place as if he didn't see her beckoning, looking a little distracted.

I don't know why, when he saw this underwater site for the first time, Zhang Heng flashed a sense of déjà vu in his heart, but at first this feeling of déjà vu was not too strong, but when he came to this open-air "hall", this feeling appeared again, and this time, Zhang Heng knew where his sense of déjà vu came from.

He had a strange dream in the interracial dungeon before, in which he came to a gloomy seaside town, and when he had gathered the shadows, he returned to that seaside town again, and this feeling was like that at the time, and now, this feeling has appeared again.

Considering what happened in that town, this does not bode well.

Although this dive site is quite famous, it receives many tourists every year, and no one has had any accidents here so far, but Zhang Heng does not want to doubt his instinctive awareness.

After that, he decisively gave a thumbs up to Han Lu and Neri and asked to rise.

Nelly felt a little strange, she didn't know why Zhang Heng suddenly stopped this dive, and wanted to gesture to ask Zhang Heng what difficulties he encountered, but Han Lu was more experienced, she and Zhang Heng had unconditional trust in the latter after experiencing the death dream incident together, and she also knew that there was another more crazy and dark world hidden under the ordinary world.

Therefore, seeing this, he did not question why Zhang Heng made such a decision, but immediately made a firm gesture of rising.

But then I saw that Nelly's face suddenly changed, and she made a downward gesture anxiously.