At first, I could not see anything.
The sudden brightness was almost unbearable after so long in darkness. My eyes had become so used to the gloom that I had to close them again.
When I finally opened them, I could only stand there in stunned silence.
Nothing I had ever imagined could have prepared me for what I saw.
“The sea—the sea!” I cried.
“Yes,” my uncle replied proudly. “The Central Sea. No future navigator will be able to deny that I discovered it. That means I have the right to give it a name.”
He was absolutely right.
Before us stretched an enormous body of water. It was so vast that I could not see where it ended. Perhaps it was a lake. Perhaps it was an ocean.
The shoreline curved in and out, covered with soft golden sand and countless little shells. Some of those shells had probably belonged to creatures that had disappeared from the earth ages ago.
The waves rolled onto the shore without stopping.
Their sound was strange and deep, made even more powerful by the enormous underground cavern.
A light wind moved across the clear water, raising little waves and sending drops of spray against my face.
Above us, an enormous wall and roof of rock rose to an unbelievable height. Only a narrow opening could be seen overhead, but the beach where we stood was surprisingly wide.
Huge cliffs, rocky points, and towering promontories surrounded the sea. After countless ages of waves crashing against them, their surfaces had been worn smooth.
Farther away, the rocks seemed to disappear into a thin mist.
It really was an ocean.
But it was unlike any ocean I had ever known.
It was cold, harsh, and frighteningly wild.
One thing puzzled me more than anything else.
How could I see all this?
We were deep beneath the earth. We should have been surrounded by complete darkness.
Yet the entire landscape was illuminated as clearly as if it were daytime.
But the light was nothing like sunlight.
There was no golden warmth, no dazzling brightness, no moonlight, and no stars.
The light was pale, cold, and strangely white. It seemed to flicker constantly.
My uncle and I quickly realized that it must be some form of electrical light, perhaps something similar to the northern lights, except that here it never disappeared.
It was powerful enough to illuminate the entire underground ocean.
Above our heads, the enormous ceiling seemed to be covered by clouds.
Thick, misty masses drifted slowly through the darkness. They were constantly changing shape.
I had once believed that the tremendous pressure so far beneath the earth would make evaporation impossible. Yet somehow, clouds had formed here.
Electric currents moved through them, creating astonishing patterns of light.
One moment, deep shadows covered the distant rocks.
The next, a brilliant ray of light appeared between two clouds.
It was beautiful, but it gave off no heat.
The whole scene was strangely sad.
Instead of a beautiful blue sky filled with stars, I saw an enormous roof of dark granite hanging above me.
It seemed to press down on my mind.
As I looked around, I suddenly remembered an old theory proposed by an English captain.
He had imagined that the earth might be a huge hollow sphere, with air trapped inside it and kept luminous by atmospheric pressure. According to his strange theory, two stars called Pluto and Proserpine moved through this inner world.
What if the old captain had actually been right?
We were certainly trapped inside an enormous hollow space.
I could not see how wide it was. The shoreline stretched away in both directions and eventually disappeared into the distance.
I could not tell how long the sea was either.
A thick haze covered the far horizon.
As for the height of the cavern, it was impossible to measure. The roof had to be many miles above us.
Looking upward, I could not even tell exactly where the ceiling began.
The lowest clouds seemed to float nearly two thousand yards above us.
I can only call this place a cavern because I have no better word.
Its size and terrible beauty were beyond anything human language could describe.
Perhaps it had been created when the earth cooled and enormous sections of its interior collapsed.
I had read about some of the world’s greatest caves, but none of them could possibly compare with this place.
The great Guacharo Cave in Colombia, which Humboldt had explored, seemed like a tiny hole beside it.
The enormous Mammoth Cave in Kentucky was equally insignificant.
Here I stood before a cavern filled with clouds, strange electric light, and a vast underground ocean.
Only imagination could truly convey its size.
I stood there in complete silence.
I had no words for what I was feeling.
It was almost as if I had suddenly become an inhabitant of another planet and had arrived on Earth for the first time.
Everything around me seemed to belong to another world.
I wanted to describe what I saw, but ordinary words were not enough.
So I simply stared.
I thought.
I wondered.
I admired.
And beneath all that wonder, I could not completely suppress my fear.
Yet the sight of this new world seemed to restore my strength.
Some color returned to my face.
The strange atmosphere also seemed to revive me. The air was dense but lively, and every breath filled my lungs with unfamiliar freshness.
After forty-seven days trapped in dark and miserable tunnels, breathing this salty air was an extraordinary pleasure.
It reminded me of standing beside the sea on the surface of the earth.
My uncle had already recovered from his first surprise.
He was once again completely himself.
“Well,” he said after giving me plenty of time to admire the underground sea, “do you feel strong enough to walk?”
“Certainly,” I replied at once. “I would love to.”
“Then lean on my arm, Harry. Let us take a walk along the beach.”
I gladly accepted his help.
Together, we started walking along the shore.
On our left, enormous rocks were piled one above another, forming a gigantic natural wall.
Waterfalls poured down their sides from countless heights.
When they reached the bottom, they became clear, murmuring streams and flowed into the great lake.
Here and there, thin clouds of steam rose from the rocks.
They drifted through the air like pieces of wool.
They seemed to come from hot springs, whose water eventually flowed into the underground sea.
Then I recognized one of the streams.
It was our old friend, the Hansbach.
After all the difficulties it had led us through, it now disappeared into this enormous basin as if it had been flowing there since the beginning of the world.
“We are going to miss our good friend,” I said with a sigh.
“Bah!” my uncle replied impatiently. “What difference does it make? That stream or another one—it is all the same.”
I thought his answer was rather ungrateful.
I almost told him so, but decided to remain silent.
A moment later, something completely unexpected caught my attention.
We had walked perhaps five hundred yards when we rounded a steep rocky point.
Suddenly, we found ourselves facing a tall forest.
The trees had straight trunks and enormous tops shaped like umbrellas.
The strangest thing was that they did not move at all.
A fairly strong breeze was blowing, yet the trees stood perfectly still, as if they had been turned to stone.
I hurried toward them.
I had no idea what kind of trees they were.
Were they one of the thousands of species already known to science?
Or had we discovered a completely new kind of plant?
When we finally reached the forest and stood beneath the enormous trees, my surprise turned into admiration.
My uncle immediately recognized them.
“They are nothing more than mushrooms,” he said calmly.
“Mushrooms?”
“Yes. A forest of mushrooms.”
He was right.
They were ordinary mushrooms—but on a gigantic scale.
I had heard that the giant puffball mushroom could grow to a circumference of nine feet.
But these mushrooms were nearly forty feet high, and their caps were just as enormous.
Thousands upon thousands of them grew together.
Their huge bodies blocked almost all the light.
Beneath their enormous caps was a dark, mysterious world.
I still wanted to explore farther.
But the temperature beneath the mushrooms was surprisingly cold.
For almost an hour, we wandered through that strange darkness.
At last, I had enough and returned to the shore, where there was more light and warmth.
But the mushrooms were only the beginning.
The underground world contained many more wonders.
We had gone only a few hundred yards when we discovered another enormous group of plants.
These were recognizable as ordinary plants from the surface world—but they had grown to unbelievable sizes.
There were lycopods a hundred feet tall.
Ferns as tall as pine trees.
Grasses larger than anything I had ever seen.
My uncle could hardly contain himself.
“Amazing! Magnificent! Extraordinary!”
He pointed excitedly at the enormous plants.
“Harry, we are looking at the entire plant world of an ancient age of the earth! These tiny plants that we see in modern gardens were once enormous trees. Look around you! No botanist has ever seen anything like this!”
His excitement was completely understandable.
“You are right, Uncle,” I said. “It is almost as if nature preserved an entire ancient world inside this enormous underground greenhouse. It is a living example of what scientists have only been able to reconstruct from fossils and drawings.”
“Well said, my boy. Very well said!”
He looked around proudly.
“And you would also be right to call this place something else.”
“What?”
“A huge zoo.”
I looked around nervously.
“A zoo?”
“Of course. Look at the ground beneath our feet.”
I followed his gaze.
“Look at all those bones along the shore.”
“Bones,” I said.
“Yes. The bones of prehistoric animals.”
I bent down and picked up several strange remains.
They were unmistakably ancient.
Some of the bones were enormous, almost as large as tree trunks.
I became excited too.
“This is the lower jaw of a mastodon!”
I picked up another bone.
“These are teeth from a Dinotherium.”
Then I examined another.
“And this is part of a Megatherium’s leg.”
I looked at my uncle.
“You were right. This really is a zoo. The enormous animals that owned these bones must once have lived and died beside this underground sea, beneath these giant plants.”
I pointed toward several complete skeletons.
“There are entire skeletons over there. And yet…”
My voice stopped.
“And yet what?” my uncle asked.
“I don’t understand how such animals could have lived inside a granite cavern, especially at this incredible depth.”
“Why not?”
“Because animal life appeared during the later periods of earth’s history, after sedimentary soil had formed. It was the sediment that replaced the hot, burning rocks of the earth’s earliest age.”
My uncle listened patiently.
Then he gave me his answer.
“Harry, your objection is easy to explain. The ground beneath us is sedimentary soil.”
I stared at him.
“How could sedimentary soil exist this deep beneath the surface?”
“It can be explained quite simply. There was a time when the earth had only a thin, unstable crust. Because of the force of gravity, parts of that crust rose while others sank.”
He pointed toward the enormous cavern.
“During that period, huge landslides must have occurred. Entire sections of sedimentary ground could have fallen into enormous underground chasms.”
“That is possible,” I admitted.
Then I looked around uneasily.
“But if prehistoric animals once lived down here, what is to stop one of those monsters from hiding behind one of those rocks right now?”
As I spoke, I carefully examined the surrounding cliffs.
I searched every part of the horizon.
But there was no sign of anything alive.
By then, I was exhausted.
The walk and the excitement had been too much for me in my weakened condition.
I told my uncle that I needed to rest.
I sat down at the end of a rocky promontory where the waves broke endlessly below.
In front of me was a wide bay surrounded by enormous granite formations.
At the far end was a small natural harbor protected by gigantic piles of stone.
It was large enough for several sailing ships to anchor safely.
The harbor looked so natural that my imagination began playing tricks on me.
For a moment, I almost expected to see a ship appear in the distance, its sails spread wide as it sailed toward us on a warm southern wind.
But the illusion never lasted long.
There were no ships.
There were no people.
There were no animals.
We were the only living creatures in this underground world.
Sometimes the wind stopped completely.
Then an even deeper silence fell over the cavern.
It was more terrible than the silence of any desert.
The barren rocks seemed frozen beneath the heavy silence, while the strange sea became perfectly still.
I stared through the distant mist, desperately trying to see what lay beyond it.
What was hidden behind that veil?
Where did this enormous sea end?
What was on the other side?
Would we ever reach its distant shores?
I had countless questions, but no answers.
My uncle, however, had no doubts.
He was certain that our expedition would eventually succeed.
I was not so confident.
Part of me desperately wanted to continue.
Another part of me was afraid of what we might discover.
After we had spent more than an hour silently admiring this extraordinary world, we finally got up and returned toward the grotto.
I was relieved to reach it.
We ate a small meal.
Then I lay down and tried to sleep.
After many restless struggles, exhaustion finally overcame me.
At last, I closed my weary eyes and fell asleep.