Under Duncan's slightly unfamiliar and cautious control, the submersible slowly adjusted its direction.

The "base" beneath the Frost City-State was like a vast, boundless, rough and strange cliff in the sea, moving slowly in the dim sea water outside the porthole.

The sunlight shining from the sea above has faded, and the only light beams left in the water are from three sets of large searchlights in front of the submersible. The light beams are projected into huge spots on the surface of the "cliff", and beyond the spots, there is unknown darkness.

From time to time, a low hum and the hissing sound of certain valves automatically adjusting the air pressure can be heard in the ears, and these monotonous and lifeless sounds make people feel more... lonely.

It is the loneliness that comes from an individual being away from the group and a mind being away from the boundaries of civilization. It is the anxiety that comes from gradually sinking into endless darkness and being enveloped by the endless sea.

Agatha fell silent. She stood in front of the porthole and stared at one direction outside for a long time. After an unknown amount of time, she broke the silence with a soft voice: "All the light is fading... but I can still 'see' the base of the city-state. It still emits a very faint light. It is the only thing I can see in the darkness."

The world she observed was obviously different from that of ordinary people.

"Do you know what I'm thinking?" Duncan's voice suddenly came from behind her.

"What are you thinking about?"

"I think this may be the way we observe the world," Duncan said in a slow voice, as if blending into the humming of the surrounding machines, "The world is like an ocean, and if we regard the entire civilization as a whole, we are like diving in such a boundless abyss.

“The unknown darkness covers the entire world. We carefully peek at the scenery that occasionally emerges from the darkness from the lights of civilization, and try to speculate and piece together the outline of the entire world from those fleeting images. However, we almost never have the opportunity to truly understand the whole truth behind those lights and shadows.

“Behind a small fallen leaf may be an entire forest, behind a stubborn rock stands an entire mountain, and a vine passing by in the light may just be a tentacle extended by a mythical beast - beyond the glimmer is the unknown, and within the glimmer is just a partial impression of the truth presented to us at a specific location and time.

"And it was during this cautious voyage that some people accidentally glimpsed the part beyond the light, so they went crazy. Some people tried to expand the light, and we called them pioneers. In many cases, there was not even a clear boundary between these pioneers and lunatics. As for more people, they gathered inside the ark of 'civilization', gathered in the limited light that was enough to illuminate their feet, lowered their heads, and carefully focused their sight.

"They are called 'ordinary people'.

"The world they know and know brings them a precious sense of security, so they can no longer look at the darkness outside the Ark... But it is these ordinary people, who make up the largest proportion, who are weak and powerless, who maintain the operation of the entire Ark and even support those pioneers and lunatics."

The sound of seawater being injected into the pressure tank came from under the feet. The submersible slowly adjusted its angle and began to dive faster. Outside the observation window in front, within the light spot cast by the searchlight, the undulating cliffs continued to rise upwards - in the next second, the scenery in the light spot might turn into an empty dark body of water, but it might not.

Duncan withdrew his gaze and looked around him.

With lights pouring down from above, everything in the submersible is bathed in light, and after staring at the darkness outside for too long, a glance back at this cozy cabin does give one a genuine sense of relief.

But the occasional "creaking" sound coming from somewhere in the hull constantly reminds the people in the crew cabin that there is only a layer of fragile spherical steel plate between this comfortable and bright cabin and the billions of tons of sea water outside.

This fragile spherical shell steel plate was hammered and cast bit by bit by countless "ordinary people". Those craftsmen who might never step out of the city-state in their entire lives used their skills and wisdom to send this simple submersible into the endless abyss below the city-state.

Agatha was silent for a long time, then spoke softly: "Actually... I sometimes feel fortunate that my eyes can now see more than ordinary people. Just like you said, we are all diving in the endless darkness, so my eyes can now see farther in places where the light can't reach. But I often feel frustrated, because compared to this endless darkness, this slightly farther field of vision seems meaningless..."

"Yes, for this boundless ocean, a slightly farther view is insignificant," Duncan said softly, but then he changed the subject, "But for us who are diving in the dark, even if we can only see one meter further, it is of great significance."

He casually turned off the main lighting in the cabin, leaving only the necessary lights on the operating console.

It became dark inside the submersible, but as the contrast of the lights changed, the beam of light from the high-power searchlight in the darkness outside the porthole appeared brighter and brighter. Within the range of that light spot, the details of the surface of the "cliff" became clearer and clearer.

"The world you describe is almost hopeless, but your attitude seems to be always optimistic," Agatha said, "This makes me... a little surprised."

"I described a hopeless world to you because it is such a bad world. I am optimistic because I am an optimistic person," Duncan said casually. "We cannot change the world, but our attitude belongs to us."

"I didn't expect you to have such a personality, and I didn't expect you to be so sentimental," Agatha seemed to smile. "Yes, I always forget that you are the greatest explorer in the world."

Duncan just smiled and didn't respond. His eyes were fixed on the porthole. With the help of the beam of light from the searchlight, he carefully observed the gradually rising "cliff".

The texture looks like stone, with some parasites like seaweed and coral clinging to the surface.

But such a vertical structure and such a regular "base" do not look like something formed naturally.

He steered the submersible forward carefully, and stopped it at a very close distance. Then, he found a control lever on the console with a bit of unfamiliarity, and released the mechanical arm right in front of the submersible.

In the light, the robotic arm slowly unfolded, and the sharp structure at its end touched the "cliff" in front, tapping and scraping it gently.

Some debris fell slowly into the water.

But the interior of the debris appears to be a more solid structure.

"I've always been curious about one thing," Duncan suddenly broke the silence. "Over the years, in so many city-states, there has always been a lack of digging deep underground - whether it's mining, building underground facilities, or simply research... Has no one ever dug through this 'foundation'?"

Agatha was stunned for a moment. This question seemed a bit out of line for her. But after a brief thought, she shook her head and said, "As far as I know... there has never been such a 'dig through' situation. Because underground is dangerous. The lower the place is below sea level, the higher the probability of abnormal changes in the darkness. Even with the protection of steam and flames, mental pollution and strange accidents happen in the mines every year, not to mention digging deeper with the crazy idea of ​​'drilling through the city-state', and..."

She paused, sorted out her memories, and then continued, "And even if you really hold on to this crazy idea and dig deeper, it seems that no one has ever succeeded. I have heard that the Academy of Truth has tried this, and their conclusion is... when digging to a certain depth, the drill bit can no longer penetrate. The deeper you go, the harder it gets, until even the hardest and most advanced drill bits break."

"It gets harder the deeper you go?" Duncan frowned and turned to look at the mechanical arm outside the porthole that was knocking on the "cliff". It had now knocked off some attachments, and after the loose debris fell off, the inner layer of the cliff revealed a darker and denser structure.

Can't tell if it's rock or metal.

But its surface seems to have vague and regular patterns, just like... the grooves on the skin of some creature.

Duncan operated the robotic arm, trying to scrape some samples from the dense black structure, but to no avail.

The robotic arm is underpowered, and the layer of black substance is harder than expected...some kind of "bottom shell"?

All kinds of speculations arose in Duncan's mind, and he even came up with some bold exploration plans, but in the end he tried hard to suppress his curiosity and began to control the submersible to continue moving into the deep sea.

After all, exploring the "huge unknown entity" directly beneath the frost is his primary goal of this trip. Without being sure whether there will be a second chance for a deep dive, he cannot waste the submersible's precious battery life halfway.

The submersible continued to dive, accompanied by noise from the ballast tank.

After an unknown amount of time, they finally crossed the "fault" under the foundation of the city-state.

Very suddenly, the "cliff" within the range of the searchlight came to an abrupt end, and the huge spot of light seemed to be suddenly swallowed up by the darkness, followed by an endless body of dark water.

No matter how powerful the searchlight was, it was impossible to find a target in such a vast sea. Duncan could only see a hazy boundary of light and shadow extending outside the porthole, but no reference object could be seen either inside or outside the light.

This oppressive feeling of being trapped in the vast darkness and sinking continuously is far better than facing the strange huge hole deep in the boiling gold mine.

Agatha also gripped the armrest in front of her nervously.

The last glimmer of light in her "vision" disappeared.