To Yang Jing's surprise, after opening the heavy watertight door, there was a circular passage with a diameter of about two meters behind the door. The passage was made of special steel, four or five meters long. On the opposite side of the passage, there was also a circular watertight door.

When Yang Jing saw this structure, he immediately realized what the circular passage and the watertight doors at both ends of the passage are used for.

Most of the base is below sea level, and before it was established, it was a natural cave formed when a volcano erupted.

Because there is no other place in the cave that can communicate with the outside world, enough air pressure is formed in the upper half of the cave so that the sea water will not surge from below the cave.

However, this cave must have been accidentally discovered by Takijiro Oshi. Because it was extremely hidden, Takijiro Oshi decided to convert this natural cave into a secret underwater base.

But you can't just walk underwater when entering and exiting the base? After all, the steel gate is for submarines to enter and exit, and the water is too deep, so it is impossible for soldiers who are on duty in the base to enter and exit through the underwater gate. Therefore, these soldiers who are on duty in the base must enter and exit the base from other places. Moreover, the import and export must be on the island, not in the water.

But once you want to make a hole in this originally sealed cave, the air in the cave will inevitably be discharged by the sea water, and the sea water in the cave will be at the same level as the sea level outside, and the base will lose its function.

Even if Takijiro Oshiki doesn't understand this most basic physical principle, the engineers responsible for building this base must understand it. So in order to avoid this situation, the engineers set up such a passage similar to an airtight cabin here.

When someone comes in and out, open a door first, and enter the passage, then close the first door, and then open the second door. In this way, the air in the hole will not leak out.

These two watertight doors and this circular passage play such a transitional role.

Moreover, although he had not inspected the base carefully and did not see relevant oxygen-generating equipment just now, Yang Jing was sure that there was definitely an oxygen-generating machine in the base. After all, an oxygen-generating machine was researched by the Germans as early as the beginning of the last century. Although only Germans and French in the world were able to make industrial-grade oxygen-generating machines before the 1930s, with the outbreak of World War II, the Japanese also learned the production process of oxygen-generating machines from the Germans early on.

This base was established in the 1940s, so it is absolutely impossible for the base to lack oxygen generators. Because the oxygen generator can not only generate a steady stream of oxygen for the base, but also continuously replenish the air pressure consumed by the base due to personnel entering and leaving.

After understanding the function of this passage and the two watertight doors, Yang Jing closed the first door to death, then walked to another door and opened the second door.

There are still natural caves outside the door, but there are several military barracks, which should be the Japanese barracks guarding the base.

After walking forward for about forty meters along the road between the barracks, a slanted upward ladder appeared in sight. Looking up, the slanted ladder extended upward for more than 30 meters, with a height of about fifteen meters. At the top of the slanted ladder, there was still a round watertight door.

Obviously, this inclined ladder and the watertight door at the end of the inclined ladder are the entrances and exits to the outside world.

Yang Jing looked back at the base he was walking over, and probably drew out the structure of the base in his mind.

This base was built on a natural cave. The widest part is at the southernmost point of the cave, which is the other side of the boat platform. The width between the east and west is more than 100 meters, and the height of the cave is also the largest, at least forty or fifty meters high.

Then the base extends northward, the narrower the width the northward, and the height of the cave is constantly decreasing. Until more than 200 meters away, the base becomes more than 40 meters wide and fifteen meters high. Overall, the base is a bit similar to a trapezoidal cube.

Yang Jing shook his arm, then grabbed the ladder and started climbing upwards. After reaching the watertight door at the end of the ladder, Yang Jing tried to twist the knob on the watertight door. With a sound that made the teeth sore, the watertight door finally began to move.

When Yang Jing twisted the knob to the end, the watertight door was completely opened, but the watertight door was very heavy. Even with Yang Jing's strength, he used a lot of effort to finally open the watertight door.

The moment the door opened, the sunlight rushed in from outside with a hot air. After Yang Jing climbed out, he found that he was at the gentle slope on the west side of Maogexi Island near the foot of the mountain.

After drilling out, I found that there were mud and several rocks scattered beside the door. No wonder this door was so heavy. It turned out that the door was covered with at least half a meter of soil, and a few rocks rolling down from the mountain were also pressed on it.

If it were someone else, I would probably not be able to open the door below.

No wonder Chris and his team had not found the entrance to search for the base on this island. The door was buried under the soil, and they did not have the instruments specifically used to detect metals. Moreover, the door was small and almost negligible compared to the entire western island. How could Chris find this door?

Yang Jing stood next to the door, took off his mask, took a deep breath, and then started calling Chris and the others via radio.

After a while, Chris and the others took a motorboat and walked out of the lagoon. When they saw Yang Jing standing at the foot of the mountain, their faces were strange.

After getting off the motorboat, several bodyguards trotted to Yang Jing. Chris asked strangely: "BOSS, we didn't see you coming out of the water, why are you standing here?"

Kevin Martin on the side said with a confused look on his face: "BOSS, can you use the kind of shifting and transposition in "Harry Potter"?"

Yang Jing pointed to the big hole beside him with laughter and cry, and then the few people saw the open circular watertight door.

"BOSS, is this the entrance to the base?" Thomas asked in disbelief, slapped his forehead, "I went up the mountain from here yesterday, why didn't I see this door?"

Yang Jing was too lazy to explain, but said, "This door leads to the base below. There are two entrances and exits in the base below, one in the water and one here. By the way, have George and Clark come up?"

"Not yet, but it's too soon, Sean and Mark are staring there."

Yang Jing nodded and said, "Let's take a break first, and after George and the others come up, we will go down from here!"
Chapter completed!