The water had become unusually cold, after all, in front of them, there was an unknown thickness of ice walls, so the ice water mixture had made the water temperature of the dark river close to zero degrees Celsius.

However, this is still not the most important problem, as the water level continues to rise, there is not much space for them to poke their heads out of the water and breathe in the not spacious cave, so after they enter it, they can only raise their heads, put their mouths and nostrils as far as possible out of the water, breathe a breath of air, and then dive into the water again, groping their way forward in the dark.

Soon, however, they found that even their nostrils could hardly get out of the water, because the water level had risen, and there was hardly any air between the cave and the water.

When Gao Chao found out this, he was a little panicked in his heart, but soon, the strict psychological training he had undergone in the army calmed him down, and he picked up a flashlight and shone it above the top of the cave, which was already completely covered with water, but because the water level rose quickly, there were many air bubbles left on the uneven roof of the cave.

Gao Chao immediately looked back at Xiao Liu and Da Liu, and motioned with his hand for them to look at the bubbles.

Obviously, Xiao Liu and Da Liu were also a little panicked, and they didn't understand Gao Chao's thoughts at the first time.

When Gao Chao saw them like this, he immediately swam upward, in order to give them an example.

I saw Gao Chao swim his body, and soon touched the position of the top of the cave, and then, he actually raised his head and used his mouth to touch the bubbles on the top of the cave, only to see that he first exhaled a breath of air, and the huge bubbles were blown by him, and then he immediately used his mouth to suck the bubbles on the top of the cave.

It turned out that Gao Chao was using those bubbles to breathe, and those bubbles were also air.

Seeing Gao Chao like this, Xiao Liu and Da Liu stabilized a lot, and they immediately learned to be superb, putting their faces as close to the top of the cave as possible, and then they both breathed air smoothly.

In this way, although they no longer had any space to breathe, fortunately, the uneven roof of the cave saved them.

Then, the three of them continued to swim forward, only to find that the tunnel-like thing was getting narrower and narrower, and the place where they could swim normally soon became only to lay their bodies flat and swim on their backs.

Why swim on your back? The reason for this is because they have to constantly breathe in the bubbles on the roof of the cave in order to breathe and maintain their oxygen uptake.

And Gao Chao has been swimming at the forefront, of course, his pressure is huge, now, they have no way to retreat, because even if they can retreat, but the bubbles on the roof of the cave have been breathed by all of them, and what is left behind is only carbon dioxide, that is, they have no regret medicine to take now.

Ahead, it's dark, and the superb flashlight doesn't shine far here.

This underground tunnel of the dark river is so cold and clear that the water is like a vacuum that does not exist, and Gao even has an illusion, he feels that they are flying, flying in the endless darkness.

Suddenly, Gao Chao's body trembled, his eyesight under the water was not so good, but he was still very sensitive to light.

Suddenly, he noticed that in the darkness directly in front of him, there was a faint light, which seemed to flicker like nothing.

Is it an animal? Or maybe it's fish?

Gao Chao was muttering to himself, maybe it was a creature, he raised his vigilance, but it didn't make him feel much hope of survival, in other words, he still had a huge pressure in his heart right now.

However, as the vague light got closer, Gao Chao's heartbeat also accelerated, as he noticed that the water around him seemed to be warming.

He suddenly became vigilant, although the temperature rise may be a good thing, but in Gao Chao's view, it can also be a bad thing.

Because he understands that if they go in cold water for a long time, it is easy for them to suffer from hypothermia, and one of the characteristics of hypothermia is that people hallucinate in that environment.

You must know that once the body temperature of the human body drops by one degree, it will be extremely fatal.

However, as Gao Chao was trying his best to get rid of his hallucination, he found that he had swam to the location of the light.

Suddenly, the surroundings were inexplicably warm, and the light seemed to be shining down from above, and Gao Chao realized that the blurred light just now was not a cave creature or anything at all.

However, Gao Chao panicked even more, he felt that his hypothermia was about to reach a fatal moment, because he had hallucinations in vision and body sensation at the same time, and it seemed that this time it was really going to be over.

But just as Gao Chao's heart was racing, someone patted him on the shoulder, and he felt that someone was tugging on his shoulder and pulling him upward.

Gao Chao looked up at this time, and his vision in the water was blurred, but he realized that the person was none other than Da Liu.

At the same time, the soft light seemed to be above, and the three of them were swimming upward, and the originally narrow passage seemed to have become upward, and it seemed that the light was getting brighter and brighter.

- On the calm water, there doesn't seem to be a ripple.

And above this calm water, there is a splendid palace.

There was no doubt that the palace was underground, but it was bathed in a soft light, a light that seemed to be as warm as the sun, but it was not sunlight, it was the light from the top of the tall cavern.

The stone wall at the top of the cave was translucent, and on it, it seemed that the sunlight was shining through, illuminating the entire huge cave.

Suddenly, on the calm water, there was a violent splash, and then three people showed their bodies.

As soon as they burst out of the water, they violently began to breathe in the air of the cave, then coughed violently, and then they gradually calmed down.

"I'm grass!" One of the biggest men, of course he was Da Liu, and he finally said the first sentence: "Where the is this?" How can there be a ...... here? And sunshine? ”

As he spoke, Da Liu swam on the water and raised his head to look at the top.

Although everything here is too much to admire, for the master who is also exposed to the water, it is the palace on the water's edge that cares about it.

Only Koyanagi swam and said, "It seems to be glass, and the sunlight is shining through it." ”

Da Liu glanced at Xiao Liu and said, "Don't talk nonsense, how can this be glass, I think it's more like crystal." ”

Gao Chao said at this time: "No, it's not crystal, such light transmittance, it can't be crystal." ”

Da Liu looked at Gao Chao and said, "What could it be?" ”

Gao Chao said: "Maybe it's quartz, that kind of translucent thing, the light transmittance is not good. ”

Xiao Liu nodded and said: "Don't say it, in the end, Lao Gao knows a lot, this thing has a mine over there in our house, it is indeed translucent, and it is really that kind of thing." ”

Da Liu pursed his lips, and then said: "That's strange, it should be a desert on this, how can there be such a big piece of quartz?" When the sun shines through, the people above should be able to spot it. ”

Gao Chao thought for a moment and said, "Maybe it's because on top of this quartz, it's very likely to be a lake. ”

"Huh?" Da Liu said: "This is true, if it is a lake, others will not be able to find it, and it is also transparent, it must be like this." ”

Gao Chao said at this time: "Okay, don't worry about this for now, you look at that palace, I think this is the place we are looking for." ”