In the interior of a karst cave, Bai Yujing opened a silver-white suitcase, turned on the computer, opened a software, entered the password and control program, Bai Yujing saw that several drones in the box all flew the machine, and then flew out on their own.

Bai Yujing pressed the Bluetooth headset on his ear: "Li Hao, is this how you use it?"

Li Hao on the other end of the phone immediately said: "That's right, it's okay to explore the surrounding terrain by flying out, they will explore the surrounding terrain and record it on their own, you can wait for them to fly back, try a few more times, and you can detect the terrain of the underground cave you said, how many karst caves there are, what the underground passage is like, and what the terrain is, you can see it clearly." ”

Bai Yujing started by making a phone call Li Hao asked to see if there was a solution to this kind of terrain, but he didn't expect this guy to directly send him a set of this terrain detection drone, which looked quite advanced.

"That's your loneliness, watch more news, this kind of terrain detection robot has been there for a long time, no one needs to control it, it will collect the surrounding caves and terrain through the infrared rays emitted, even in the underground and extremely complex terrain can be used, and it will automatically fly back within half an hour. ”

"Okay, I'll take a look!"

Bai Yujing didn't understand anything, listened to Li Hao's explanation, took the manual and read it, and probably understood how to use this thing, after hanging up the phone, he waited for a long time, and watched those exploration drones fly back one by one, and after gathering the detected information to the computer little by little, he immediately saw a complex underground network topographic map immediately appear on the computer screen.

Zhou Jun posted it and took a look: "This thing is so advanced now, this high-tech, I haven't played it before!"

Bai Yujing said to Qian Jia: "Where is the geological water vein map you got before? Bring it to me and show it!"

Qian Jia immediately pulled out the drawing from his backpack, Bai Yujing looked at it carefully, and then took a compass to check the direction: "Well, the largest underground dark river is here, according to the network topographic map of the underground cave, it should be entered from this karst cave, at a depth of one thousand meters underground, the place where this dark river is is really deep enough!"

Bai Yujing took a look, pointed to the entrance of a karst cave in the lower left, and said to Qian Jia and Zhou Jun, Qian Jia immediately said with his backpack on his back: "Okay, let's hurry up!"

Bai Yujing immediately stopped Qian Jia: "Don't, Zhou Jun and I can go in, you and Xiao Jin will stay outside and wait for us, this is a thousand meters underground, the complex underground network and karst caves, we don't know how long it will take, and it is estimated that we will not be able to climb out in a day or two, not to mention that we have to find the tomb of King Yu through the underground river, so don't make trouble for us!"

Xiao Jin kept nodding her head, looking at the dark cave and cave entrance below, dark and damp, who knows what was inside, letting her drill this kind of place was almost like killing her.

Qian Jia thought for a while, he really had no experience in polar survival, the danger of this kind of underground cave was even more extreme than that of many polar regions, and going down by himself really couldn't help Bai Yujing, but would only add to the chaos.

Qian Jia nodded: "That's okay, we'll wait for you outside, you must come back!"

Bai Yujing nodded, sat on the ground, and after importing the topographic map of the underground cave in the computer into the mobile phone, he loaded the silver-white box and said to Zhou Jun: "Check the equipment, we are ready to go down!"

Qian Jia looked at the two people carrying heavy backpacks and preparing to go deep into the cave in their jackets, and said worriedly: "Is it enough to bring two pistols, you said, there may be danger inside, should we wait a little longer, find more people to come over, and go down together?"

Bai Yujing shook his head: "Okay, don't worry, I not only brought a pistol, but also other preparations, and the so-called danger does not necessarily mean that there are things inside, dangerous terrain, organs, natural hazards, these things are useless with guns, but Zhou Jun and I are both very strong in physical fitness and very experienced, we all know how to deal with this situation, you go back!"

Bai Yujing then took Zhou Jun and the two of them, turned on the searchlight on the hard hat, walked down without hesitation, and drilled into the dark cave, with the crisp footsteps and the sound of water droplets, the light also disappeared little by little in the outermost big karst cave.

This cave is a downhill slope, and the stones under your feet feel like a ladder, uneven, and very smooth, stepping on it always feels like you may fall down at any time, slippery, which also makes Bai Yujing and Zhou Jun walk extremely carefully.

The underground cave was dark, there was no light, and the sound of the dripping water seemed to be like a light rain that had not yet fallen, echoing throughout the cave, because the silence in the cave was incomparably louder and echoed, the sound of this water droplet was constantly amplified, and it felt like it was dripping in my heart, and there was a trace of ripples in my heart.

I don't know how many years these caves have been formed, stalactites and strange-shaped stones stand in these caves, plus underground passages formed by ground fissures and river changes, linking these caves together.

After Bai Yujing passed through two or three karst caves, the karst caves below became smaller, although it seemed that the road was quite gentle, but these karst caves were constantly going down, Bai Yujing and Zhou Jun also followed these karst caves and some small passages formed, and kept drilling down, walking for about three or four hours, and then looking down, they found a crack in the ground, which led straight to the underground,

Every time Bai Yujing walked a distance, he would take out the topographic map of the underground cave network and the geological water vein map to take a look, determine his position, and at the same time leave marks in the places he passed, so as not to get lost in this kind of underground cave.

Bai Yujing has made himself less detours in Shennongjia before, and in the fog, it is inevitable that he will get lost, go around in circles, with these signs, even if he goes wrong, it is easy to find the original way, and he will not always go around in one place.

However, when he arrived at the crack of this ground fissure, Bai Yujing stopped, after the previous terrain detection drone was released, this side only explored here, this Bai Yujing could only send out the terrain detection drone again, and go inside to see what the situation was below.

After Bai Yujing opened the silver-white box in his hand, Zhou Jun also took a flashlight and looked into the underground cave below, and immediately found something, and shouted at Bai Yujing: "Bai Yujing, come and take a look, there seems to be something down here?"

Bai Yujing immediately put down the work at hand, walked over, and took the flashlight from Zhou Jun's hand: "What's the matter?"

Bai Yujing looked down and saw this underground crack, which seemed to have traces of artificiality, and there was a wood-reinforced shelf underneath.