Advanced Cave Diving Zone

Yise continued tidying up the equipment, checking the gas cylinder pressure, and charging the batteries.

Su Ming and Simina then ventured deeper into the area.

The cave floor was extremely slippery and had many branching paths. Some areas were so narrow that only one person could pass sideways, and in some places, you couldn't even stand up straight and had to climb.

Fortunately, Simina was very familiar with it.

After the two had traveled more than two hundred meters along the rugged cave passage, a crevice appeared before them.

Su Ming peered inside and shone the light downwards. The beam pierced through the jagged rock walls and finally landed on the water surface dozens of meters away.

The water was clear, but its depth was still unclear.

"We are currently at the base of the volcanic cone."

Simina explained.

"This is the original volcanic conduit, one of the paths through which lava flowed up from below."

"The Flame-Bearing Array is located further down."

"Why is the volcanic passage passable?" Su Ming asked, puzzled. He had spent the last of his time intensively studying volcanoes.

A horizontal lava pipe, after the eruption ends, lava continues to flow out from a lower level, leaving a hollow pipe.

However, the vertical part cannot be completely cleaned; after the volcanic activity ends, it will be blocked by various residual debris.

"This passage was of course dug a thousand years ago by the Cangxiao Dynasty," Simina explained, "Otherwise, how could we enter the interior and construct the Fire-Installing Array?"

This sounds like no easy task.

"Truly impressive," Su Ming exclaimed.

Simina led Su Ming through the gap and into the alleyway.

This is a downward-sloping, irregular passage. Large sections of the rock face remain, revealing man-made fixing holes, some of which have already cracked.

The two arrived at the water's edge.

"Are we going down from here?" Su Ming asked.

Simina shook her head.

"The path down here has collapsed and is blocked." "We need to go back down via another waterway from where we just came ashore."

She said, still shaken.

"However, the route is extremely complicated, winding and dark."

No wonder those experts said that cave diving only truly begins here.

"Did you mark it?" Su Ming asked.

"Of course I did," Simina replied.

"I wonder if the marker from two years ago can still be found now," she said worriedly.

Su Ming didn't dwell on it.

"You'll find out once you explore."

****

The two then returned to the landing point.

Su Ming activated "Summoning of All Things," disassembling the Lingyu and reconstructing it into three smaller underwater probes. Dragging umbilical cables, they began a new round of mapping.

But this time the situation is much more complicated.

As the three probes continued to penetrate deeper, layers of sonar data were superimposed, revealing the terrain hidden deeper within the rock strata.

Beneath the outermost lava tube they entered lay old lava tubes formed from multiple historical eruptions.

Over the past hundreds of millions of years, layers of conduits have been superimposed on each other. As the strata were repeatedly uplifted, they were cut and connected by subsequent magma, eventually forming a complex network structure.

Intertwined, branching, converging—all at will, without any rules.

Just looking at the colorful, varied shapes on the screen made Su Ming feel dizzy.

"Three of us died in that two hundred meters of horizontal distance," Simina sighed, "All because we got lost."

Exploring the unknown always comes at a price.

However, thanks to Simina's initial exploration, the underwater probe managed to find the waterway leading to the Cangxiao Dynasty's tunnels through this tangled mess.

After entering the main tunnel, the situation suddenly changed, turning into a regular man-made passage.

The probe descended directly into the tunnel, encountering no major difficulties except for occasional bends. Simina breathed a sigh of relief.

"Fortunately, my efforts back then weren't in vain."

****

In the following period, the three unmanned underwater vehicles continued to conduct surveying, laying guide ropes and low-light markers.

The real person didn't go into the water again until the next morning.

As the three entered the side passage, the surrounding space rapidly narrowed, eventually shrinking into a narrow crevice barely wide enough for one person to pass through. The cave walls pressed in from both sides, and in some places, the width was less than a meter. The diving tanks scraped against the rocks from time to time, making a heart-stopping sound.

Su Ming tucked his arms in and slowly moved forward using his flippers.

Underwater propulsion devices are simply unusable in this scenario.

Su Ming held the rope in one hand and used the other to shield his face from the protruding rock corner, preventing it from hitting the viewing window.

The headlamp's beam was repeatedly blocked by the narrow cave walls, illuminating a distance of less than a few meters.

Ahead, Simina's flippers swayed slowly; behind her, Yise's lights shone; and beyond that, all directions were filled with rocks.

The route constantly changes direction, not only left and right, but also up and down. (This appears to be a fragment of a larger text, possibly a website or online forum. A direct translation wouldn't be meaningful without further context.)

Su Ming had only walked a dozen meters when he completely lost his sense of direction.

"Guys, I suspect I'm getting motion sickness from 3D movies," Su Ming complained.

"Theoretically, this is not possible," the expert team said. "Check the partial pressures of the gases and keep your breathing steady."

Further on, the situation worsened, as the crevice turned into a narrow cave.

Su Ming raised his head slightly, and the gas cylinder reached the top of the cave; he lowered himself slightly, and his knees brushed against the gravel at the bottom.

There's no room to turn around!

The passageway was still filled with a large amount of fine sand. Despite moving quietly, even the slightest movement of the flippers would stir up a cloud of grayish-white sediment. Visibility continued to decrease, and at one point, Yise behind them was reduced to a blurry shadow.

"Yise?" Su Ming, somewhat worried.

"I'm fine," Yise said. "I'm wondering why I used to love crawling through holes when I was a kid."

She said, half-jokingly.

"If I had gone through that experience back then, I probably would never want to touch it again in my life."

Simina would stop from time to time to check the current hydrological data, the length of the guide rope, and the direction of the luminous markers.

Su Ming and Yise also hovered in the narrow gap, like a traffic jam, as they each checked their own systems.

Once Simina finished, the "convoy" started moving again.

A section of the passage suddenly turned downwards and was blocked by a sloping rock, leaving only a gap at the bottom. Simina first removed the side-mounted equipment, pushed the gas cylinder through the gap, and then crawled through, hugging the rock face.

Su Ming followed her movements, lowering his body, but somehow got stuck somewhere.

"Don't rush, turn your shoulder to the left," Simina whispered.

Su Ming gave an OK sign, slowly exhaled, adjusted his body angle as instructed, and finally slid past the rock wall.

But there was still no sign of open space ahead; only the guide rope continued to extend into the dark waterway.

Su Ming sighed and continued walking with his head down.

Half an hour later, a relatively wide crack finally appeared in front of them.

The three of them squeezed out of the crack one by one and entered the main tunnel. The unmanned underwater vehicle followed, dragging its umbilical cable.

Su Ming wanted to let out a long sigh of relief, but was warned by the expert team behind him:

Control your breathing!

Simina brought Su Ming and Yise together, and the three of them stood quietly for a minute.

"Don't be impatient underwater," Simina said. "Any unnecessary movements will only increase gas consumption and physiological stress."

Su Ming and Yise nodded simultaneously.

"Clear."

****

The main tunnel of the Cangxiao Dynasty is about three meters high and wide, and slopes downwards.

The three people each secured a submersible and descended slowly.

"Water temperature 30 degrees Celsius, depth 110 meters," Simina reported. "Descending rate 10 meters per minute."

"Maintain balance," the commander at the rear said. "Pay attention to equalizing ear pressure." Each person was carrying three gas cylinders for this operation.

One bottle contains pure oxygen, another contains a low-oxygen mixture with a 5% oxygen content, and the third is an open-type rescue gas cylinder.

The CCR's electronic system continuously injects pure oxygen into the low-oxygen mixture based on the water depth.

However, as the water depth increases, CCR data is being continuously revised downwards, and the oxygen content in the circulating gas has decreased to 4%, far below the oxygen content required to maintain normal life in a sea-level environment.

This is because whether the human body can obtain enough oxygen depends primarily on the partial pressure of oxygen, rather than the volume percentage of oxygen in the respiratory gases.

When the partial pressure of oxygen is below 0.16 bar, the human body may experience hypoxia. When it is above 1.6 bar, oxygen toxicity of the central nervous system may occur due to excessive oxygen partial pressure.

Therefore, in diving activities, the pressure is generally controlled within the range of 0.7 to 1.3 bar.

At a water depth of 200 meters and an absolute pressure of 21 bar, only 4% oxygen content in the breathing air is needed to achieve an oxygen partial pressure of 0.8 bar, thus maintaining breathing within a comfortable range.

Simina watched the system automatically adjust itself, breathing in the warm, moist air, and was deeply moved.

"This is so much more comfortable than last time."

"It wouldn't be an exaggeration to say it's like walking on flat ground."

"How did you get down here?" Su Ming asked. "An alchemical auxiliary device, combined with the magic array 'Underwater Breathing Technique,' to exchange oxygen with the dissolved oxygen in the water."

Simina answered.

"The Pearl Duchy is a coastal nation, and we have diving technology and experience."

She told Su Ming.

"But the cave diving environment is far too complex."

"I encountered various setbacks during my practice."

"It's either hypoxia, oxygen toxicity, carbon dioxide retention, nitrogen narcosis, or decompression problems."

It took me a whole month to learn the finer details and find the balance.

She raised her wrist screen, which displayed detailed information about water depth, physiological indicators, and the current status of the CCR system.

It's clear at a glance and extremely intuitive.

"I only realize now that I survived back then entirely because of good fortune."

Su Ming was very curious. "How did the others manage to do it?"

"There's no one else," Simina replied.

"I was the only one who came down into the area of the Flame of Life Formation."

A gasp was heard from the support team at the rear.

"You're amazing!" Su Ming said sincerely.

****

In the dark tunnel, the three people and three machines slowly descended.

The rock face is covered with chisel marks, extending diagonally downwards in layers. In some areas, geological activity has caused the rock to shift and create huge cracks in the pit walls.

The water temperature rose another degree, and Su Ming felt stuffy and hot.

When the depth reached 260 meters, the surrounding space suddenly opened up, the pit walls receded outwards, and the light was no longer blocked by the rocks.

The three stood back to back, looking around.

This is a crescent-shaped underground palace; the searchlight beam cannot reach its end. But sonar can.

It clearly shows that the underground palace has a radius of about 400 meters and a total area of nearly 100,000 square meters.

Compared to its vast area, the underground palace is only five meters high.

Rows of stone pillars rise from the water, supporting the low dome. The pillars are thick and, from a distance, they look like a black forest submerged in the water.

Su Ming shone the lamp downwards.

On the ground, the unmanned underwater vehicle had already cleared away the sediment, exposing the dark brown rock surface. Countless grooves and reliefs connected one another, stretching to the horizon.

The array patterns were broad, with sharp, chiseled angles at their turns, and some of the main sections were even several meters wide. Unlike later magic arrays, which were composed of precise geometric shapes, they were more like totems directly engraved on the earth.

Dark red Magic Power flowed slowly at the bottom of the trench, sometimes bright and sometimes dim.

"Amazing!" Simina exclaimed excitedly. "This is the first time I've ever seen the whole place like this."

This time it was Su Ming's turn.

"Third Princess, calm your breathing," he reminded her.

**** Simina and Yise, as a team accompanied by a submarine, began their exploration.

Zijin's consciousness projected over and found herself hanging upside down on Su Ming's belt.

She glared at Su Ming.

Su Ming awkwardly untied the little bone dragon and then released the Star Fairy Jinxiu.

"You two form a group," he said.

Accompanied by a submarine, Zijin and Jinxiu began their inspection, staying close to the ground.

Since the entire physical array pattern has been scanned, this on-site investigation mainly focuses on interpreting the function of the array and using magic power to probe the energy flow.

Since Zijin's projection could not use Magic Power, she instructed Brocade to sense things.

As for Su Ming, he and the last submarine remained near the tunnel entrance to investigate.

Su Ming's understanding of formations was not comprehensive; he could only get a general idea.

The Flame Array is not a single plane.

There were array patterns on the pillars, and even on the ceiling. In addition to the rough runes, there were various beast carvings. Su Ming moved the light, slowly moving it around, and identified a giant beast with its head raised and roaring on a pillar.

Further away, there are giant birds with outstretched wings, huge turtles, and the largest is a coiled long snake, which occupies several pillars. They all face the center of the underground palace, tearing at each other, forming a picture of a herd of beasts spanning nearly 100,000 square meters.

Everything possessed an almost tyrannical and majestic power.

"Truly a creation of a dynasty, taking a century to complete," Su Ming remarked.

***

Su Ming suddenly felt a headache coming on, and he quickly reported it to the expert group.

After reviewing the data, the expert's diagnosis was hypercapnia.

"Your effective ventilation is insufficient, and carbon dioxide in your blood cannot be expelled," they told Su Ming. "Pay attention to your breathing rhythm; avoid shallow, rapid breathing."

Su Ming adjusted his breathing as instructed, deepening his breathing.

At sea level, the air density is 1.29 g/L.

When a gas enters water, its density increases with the increase in air pressure.

For example, at a depth of 260 meters, the air pressure is 27 times the standard atmosphere, and the air density is 35 g/L. The air resistance is extremely high, making it impossible to breathe, far exceeding the safety limit of 6.2 g/L. Even if CCR uses a large proportion of helium to replace nitrogen to reduce density during circulation, it can only maintain a level of 9-10 g/L. For a newcomer like Su Ming, who lacks experience, breathing will easily become shallower and more rapid.

Problems were almost inevitable.

"If you're still feeling unwell, try breathing with the rescue air cylinder," the expert team suggested.

Su Ming closed the valve on his mask, removed the breathing mask, touched the secondary head, and put it in his mouth.

Sure enough, this time my breathing was much easier.

The density of a gas mixture of 4% oxygen and 96% hydrogen, even at 27 times atmospheric pressure, is only about 4 g/L.

After feeling a bit better, Su Ming put the full-face breathing mask back on and began the drainage process.

"We've gone to great lengths for you rookies," the expert team said, their tone slightly smug.

****

About an hour later, everyone gathered on the inner wall of the crescent-shaped underground palace.

Even Su Ming wandered over here.

"What's wrong?" he asked the other two groups first. Simina explained.

"While suppressing the earth's ley line power, the Fire-Supporting Array is also drawing energy here."

Zijin added further:

"I believe that where we are now is merely an outer array serving as an energy tentacle."

"Behind this stone wall lies a core inner formation."

"And you?" she countered Su Ming, "Why are you investigating this place?"

"There's a sound coming from behind this stone wall," Su Ming replied.

Simina was surprised. She and Yise immediately listened intently, but they couldn't detect anything.

Su Ming shrugged.

"But the machine heard it," Su Ming replied.

He unloaded the material package from the unmanned underwater vehicle, sorted through it, and then deployed the summoning.

Several highly sensitive nodal seismographs appeared in Su Ming's hand. He tossed the seismographs to the group.

"With arrays spaced one meter apart, let's first examine the structure behind them."

By forming a dense array system of nodal seismographs, tomographic imaging of nearby strata can be performed based on various environmental noises or actively generated seismic waves.

Before long, the dense array of stations was set up.

One submersible was left on site to relay signals, while the three personnel evacuated the site and returned to the air chamber area following the decompression procedure, waiting for the dense array of sensors to collect data.

****

Later, the analysis results came out.

Inside the crescent-shaped underground palace hall, there was indeed a cavity, covering an area of approximately 20,000 square meters, with obvious traces of artificial excavation and construction.

The stone wall separating the two sides is eight meters thick and very regular, clearly indicating that when the Cangxiao Dynasty designed the Fire-Burning Array system, it was built in two separate sections.

Unlike the outer area, the inner area is dry.

"They're implementing wet and dry separation so early?" someone complained.

In addition, there is bad news. Based on the fluctuations collected by the nodal seismograph, it is clear that there are people moving inside.

As for who it is, there's no need to think about it—after all, the one who's digging up the Fire-Supporting Array right now is the Bell of Calamity, who's the real culprit.

Su Ming and the others simply followed the scent.

Simina unfolds the map.

"So, our current location is actually underground in the Blackrock Mine, and we've already run into the orcs."

The orcs have arrived, or rather, have re-arrived here.

Zijin's analysis from the magical perspective also confirmed the result.

"The outer magic circle is responsible for absorbing the earth's energy, and it's submerged in water to cool down and dissipate heat."

"The inside should be the functional area and control area."

The Fire-Burning Array is indeed an incredibly complex and ambitious project.

Looking at the 3D tomography results on the screen, Su Ming immediately had a bad idea.

He narrowed his eyes. "Do you think it would be a pleasant surprise for the Bell of Calamity and the others if we broke through this wall?"

The people nearby were taken aback.

"Practice makes perfect," Simina said. "We should go over there and see the true nature of the inner formation, and unravel this mystery."

"I still want to crawl through this hole," Yise said, eager to try.