Seeing that everyone fixed the oxygen cylinder, the shark said to everyone seriously: "Diving is actually an extremely dangerous training subject, our frogman brigade has been established for ten years, drowning happens every year, at least fifteen frogmen have become martyrs, everyone must put safety first, first of all, the water should be slow, let the body slowly adapt to the water pressure, and secondly, we must always pay attention to the change of the oxygen cylinder pressure gauge, absolutely not cut off oxygen underwater, if it is in the deep sea diving, but also to prevent underwater undercurrent, Beginners should pay special attention to the fact that when coming out of the deep sea, it must be slow, so that the pressure in the body and the pressure outside the body are gradually balanced, if the water is too fast, you will feel ear pain, and when the ear pressure balance problem is serious, it will also lead to injury to the eardrum and ear drum, if the speed of rise exceeds the speed of free rise, it will be very terrible, and the consequences are very terrible, that is, the volume of gas in the lungs suddenly expands, causing the lungs to burst. ”

"Blowing up lungs?" Listening to the shark's words, everyone couldn't help but gasp.

"Burst lungs are a sudden release of physical phenomena because of the sudden decrease in pressure in the lungs, just like the firecrackers we set off when we were children, "bang" is over with a sound, even the fish in the sea are not spared, we often see some fish with bursting abdomen on the sea, all of them burst lungs to death. In addition to the more heroic lung explosion, there is also a little gentle, that is, the legendary decompression sickness, every new diver should smell the color change, because at the beginning of training, new divers will have different degrees of decompression sickness, it usually occurs within 2-48 hours after surfacing, decompression sickness includes many different symptoms, what joint pain, limb numbness, or large red spots on the skin, may be a sign of decompression sickness, serious will leave decompression sickness sequelae, if you suffer from decompression sickness sequelaeWe will not be able to dive again for the rest of our lives, so we have to be extra careful to prevent the occurrence of decompression sickness, and we will start to enter the water. "The shark's words are a bit alarmist and suspicious.

I thought I would be able to become a frogman soon, but I didn't expect the road to become a frogman so tortuous, in order to be able to become a frogman smoothly, everyone went out, and was extra careful when entering the water, don't have a decompression sequelae, let alone burst your lungs.

The shark continued: "As a frog man, in addition to taking the risk of physical injury, the most important thing is to endure loneliness, because the vision below five meters is more blurry, and there is a sense of oppression in breathing, below fifteen meters, the light can no longer be reached, and the eyes will be dim, everyone will obviously feel the pressure in the chest, and it will become difficult to breathe, in this environment, everyone will have a sense of fear, so we should dive more than fifteen meters for the first time, and then dive to the depth after slowly adapting to it, Our deep-water diving training ground has a depth of 80 meters, and there are some plastic balls tied to the bottom of the water, if you can dive to the bottom of the sea, you can take a plastic ball, which means that you have completely become a qualified frogman, the first dive, I do not advocate that you dive to the bottom, you can dive to a depth of 50 meters, I bet that none of you will dive to the bottom of the water, I don't believe that you can try it when you dive next time, now everyone is ready to go into the water in pairs, pay attention, each group of team members can not leave their teammates, If one person does not dive, the other must stop. ”

Sun Jiashu and Zhang Ershun are in a group, for the sake of safety, Sun Jiashu repeatedly explained the matters that Zhang Ershun should pay attention to, Zhang Ershun nodded again and again, the two of them grabbed the oxygen tube with their mouths and dived into the water with their hands, before, the mouth was used to eat, but now it is used to inhale, the nose used to breathe air, but now it is useless, if there is water in the mask, you need to use your nose to suck the water out, the function has changed, and it is really a little uncomfortable to slam the water, the two of them held hands and adapted to the water for a while, and then began to sink slowly, Sure enough, as the shark said, at a depth of five meters, the two were able to see each other clearly, as the depth deepened, the vision gradually blurred, and after a while, the two fell into darkness, their bodies seemed to be wrapped in a layer of plastic film, the ear drums were slightly painful, and their breathing was also short, Sun Jiashu wanted to stop and rest for a while, but he didn't expect Zhang Ershun to pull him down vigorously, the water pressure seemed to be non-existent to him, Sun Jiashu couldn't help but secretly admire.

After diving down for a while, Sun Jiashu couldn't help it, he felt like a big stone in his chest, and hurriedly balanced the pressure inside and outside his body, so he felt a little comfortable, look at Zhang Ershun, he didn't mean to stop at all, Sun Jiashu had to passively follow Zhang Ershun and dive down.

In the monitoring room, the shark and Qin Jian were staring at the screen, most of the team members had exceeded the depth of 30 meters, indicating that everyone had already passed the first dive, most of the team members had slowed down the speed of diving, and some had stopped, and it seemed that they were ready to dive upward, but what made the shark feel incredible was that Sun Jiashu and Zhang Ershun had dived to a depth of 50 meters, although the speed of the dive was slower than before, they showed no signs of stopping, and were still approaching 60 meters.

The shark felt a burst of relief in his heart, it seemed that these team members did not disappoint him, the first dive exceeded fifty meters, remembering that when he dived for the first time, he only dived to forty-nine meters and could not dive anymore, he watched with great interest Sun Jiashu and Zhang Ershun move towards the depths.

It's more than sixty meters, the shark's relief just now began to turn into worry, Sun Jiashu and Zhang Ershun are both novices, if they continue to dive, they have no experience in how to deal with emergencies, the shark hopes that the two of them will stop diving, but Sun Jiashu and Zhang Ershun have no intention of stopping at all.

Sun Jiashu and Zhang Ershun were already close to seventy meters, and the shark's face couldn't help but ooze sweat, and he shouted into the microphone: "Sun Jiashu, Sun Jiashu, please stop and don't dive down again." ”

When Sun Jiashu heard the shark calling, he squeezed Zhang Ershun's hand, meaning to ask him to stop, because he couldn't talk in words in the water, and he couldn't see it, so he had to use physical touch to transmit the message, because there was no communication in advance, Zhang Ershun didn't understand what Sun Jiashu meant, and he thought that Sun Jiashu was encouraging him to continue diving, and dived deeper harder.

The shark watched Sun Jiashu and Zhang Ershun cross the seventy-meter marker line and continue to sprint towards the eighty-meter marker line, his face turned pale with fright, and his voice changed: "Sun Jiashu, I order you two to stop immediately." ”

Sun Jiashu stopped when he heard the shout, but Zhang Ershun didn't stop, he kept dragging Sun Jiashu to sink, his feet had touched the bottom of the water, the shark said that it was impossible for the first diver to dive to a depth of eighty meters, but Zhang Ershun easily reached it, at this time, Zhang Ershun felt extremely depressed, the strong water pressure seemed to press him into a piece of paper, although the heel has touched the bottom, but it is extremely difficult to bend down, there are many plastic balls tied to the bottom, only by taking the plastic balls out can it be proved that they have dived to the bottom, like this, the shark bet loses.

Zhang Ershun bent down with all his might, his hand touched a plastic ball, then he threw away Sun Jiashu's hand to untie the rope that fixed the plastic ball, after some efforts, Zhang Ershun untied a plastic ball, and finally succeeded, the surroundings were dark, and suddenly an endless sense of fear hit Zhang Ershun, Zhang Ershun felt that his consciousness wanted to leave him, and hurriedly reached out to grab Sun Jiashu's hand, but grabbed a void, at this time, Sun Jiashu was his only life-saving grass, this grasp, he felt a threat of death, His long-dead father can even be seen waving to him not far overhead.

"Son, come here." An old voice echoed in Zhang Ershun's ears.

"Dad, why are you here, you wait for me." Zhang Ershun's body slowly rose, rubbing Sun Jiashu's back and floating quickly.

Sun Jiashu felt that something touched his back, and knew that it was Zhang Ershun, so he hurriedly reached out and grabbed it, but grabbed a void, only to hear a frightened shout from the headset: "Sun Jiashu, quickly grab Zhang Ershun, don't let him float." ”

Sun Jiashu searched with wide eyes, there was darkness all around, he couldn't have Zhang Ershun at all, just when he was stunned to search, Zhang Ershun was already a few feet away from the top of his head.

"Sun Jiashu, hurry up, Zhang Ershun is above your head, hurry up and catch up with him." The shark reminded Sun Jiashu loudly.

Sun Jiashu listened and hurriedly kicked the water to float, as long as it was up, it was not wrong, it can be seen from the monitoring screen, Zhang Ershun kicked his feet around, it seems that he wants to leave this place of fear as soon as possible, the speed of rise is very fast, although Sun Jiashu tried his best, the two are always only one meter apart.

"Push it harder." The shark's voice was already hoarse, and if Zhang Ershun was not stopped in time and surfaced at this speed, Zhang Ershun would definitely die.

Sun Jiashu is now more than capable of strength, although he felt the water above his head rolling, knowing that Zhang Ershun was the top of his head, but he was never able to reach out and grab him.

Now it is only thirty meters from the water, if Zhang Ershun cannot be stopped within ten meters, Sun Jiashu must give up, because at this speed, Sun Jiashu will definitely die when he comes out of the water.

"Hurry, hurry up Sun Jiashu, it's too late." Sharks are going crazy.

Sun Jiashu knew that it was now a critical time, he hurriedly threw off the oxygen cylinder, really stupid, if he had thought of throwing away the oxygen cylinder earlier, I am afraid that he would have caught Zhang Ershun by now, because the oxygen cylinder has a certain weight, and if the oxygen cylinder is removed, the speed of rise must be faster, at this time, Sun Jiashu has already let it go.

"Sun Jiashu, you are looking for death, stop quickly." The shark was going crazy to see it, and in his opinion, a tragedy was about to unfold......