Dark underwater world.

Bi Fang adjusted his posture in the water, concentrated his strength on his upper body, and quickly swung his fist, which broke through the sea water and slammed into the dolphin's forehead.

The dolphin's skin was smooth and soft, and Bi Fang's punch was like a huge carbon fiber plastic plate padding the sea, quickly cutting away from the head.

Although the damage was not significant, it still made the dolphin feel pain and rolled over in the water.

It was blinded by the punch.

The bottlenose dolphin and its companion were stunned, not understanding what Bi Fang was doing, and swam beside Bi Fang, making a sharp cry in the water.

A loud in-ear loop murmur mixed with calls circulated in Bi Fang's brain, and he could feel the dolphin in front of him asking questions.

It wondered what Bi Fang was doing.

Unfortunately, the dolphin's question was not answered, but instead attracted more punches to the soles of the feet.

A few minutes later, the dolphin's tail fin slammed into Bi Fang's chest, and he and his companion flew away, ignoring the stranger he had "saved".

The huge force slapped Bi Fang on the rock wall, shattering many sandstone rubbles, but Bi Fang not only did not feel uncomfortable, but laughed.

But it hurts.

Bi Fang clutched his chest helplessly, his lungs were constantly compressed under the action of water pressure, and the dolphin's tail fin smashed directly like a battering ram, almost slapping him and vomiting blood.

At this time, Bi Fang's chest was short of breath, as if he was holding his breath too much, retching, and a little out of breath.

The bigger the animal, the stronger the strength, the black bear hunted by Bi Fang is only 300 catties, but the bottlenose dolphin just now is more than 300 kilograms, that is, 600 catties, which is twice as heavy as the previous black bear!

It sounds incredible, but it looks so fierce, and the huge black bear weighs only half the weight of the dolphins in the aquarium?

In fact, male black bears usually weigh between 60 and 200 kilograms, while male bottlenose dolphins can weigh between 300 and 650 kilograms.

The reason why the black bear looks bigger is entirely due to the visual effect of its fur and scattered limbs, and it is far inferior in quality to an adult dolphin.

In the sea, Bi Fang is not only incapacitated, but the dolphin does not have the obvious weakness of the black bear, it is better at attacking and swimming, and he does not have much chance of winning one-on-one, let alone two.

Bi Fang didn't dare to use too much force just now, for fear that if he really set the other party on fire, he might not be able to beat the other party......

Leaning against the rock wall, Bi Fang bit the breathing valve to exchange airflow constantly, soothing the knotted chest, and the huge cow harbor trevally was still stuck in the spear at this time, and its tail fin fluttered up and down with the current.

On the surface of the sea, several illuminated pleasure boats wander in the distance, and if you look closely, you can see the unique dolphin shape on the hull.

Dolphin Bay is a forbidden area, and it is rarely visited, only the nearby fishermen occasionally come back to patrol here, and even the pleasure boats will not approach easily.

Queko and Mandy stood in the shadows of the shore, not daring to show their heads, and when someone passed by, they quickly hid in the rocky reef, staring wide-eyed.

Looking at the calm sea, the two of them were anxious.

Bi Fang's strength is obvious to all, but after all, it is underwater, and underwater has never been a special session for human beings.

Sun monkeys are not good at water, let alone ordinary humans.

In addition, the opponent is a well-known water bison, which is inevitably worrying.

Mandy and Keko are great divers, a national champion, a professional instructor, and they both know a lot about underwater creatures, but that doesn't mean they can fight those creatures.

If you want to go into the water to help Bi Fang, there is nothing you can do, but there is a possibility that Mandy will encounter a situation where she will encounter a trevally in Niugang, and she will be knocked unconscious in one face and become a burden to the tuba.

"It's been ten minutes, there won't be an accident, right?"

"It's not that you don't have an oxygen cylinder, just wait."

"Hey, here!" Mandy pointed to the surface of the sea and shouted.

A wave suddenly broke on the calm sea, and Bi Fang stood on the shallow conversation, his spear resting on his shoulder, and a large fish almost a man high hung on the tip of the spear, dripping down with a mixture of blood and seawater.

Bi Fang ripped off his goggles, closed the oxygen valve, and took a big breath of fresh air from the coast, the thick salty wind poured into his lungs, feeling the heartiness that he had not seen for a long time.

The tail fin of the trevally twitched subconsciously, and Bi Fang threw it to the ground and made up for it again.

Mandy and Keko hurriedly waded into the water, looking at the cow harbor trevally that had been flooded by the sea for most of their bodies.

Mandy's hands fluttered and he shouted, "WTF, I thought you were going to beat it away, and you actually killed it directly?" ”

Bi Fang waved his hand, found a few nodes on the Niugang trevally, and pierced it with a spear.

"What are you doing? Isn't it already dead? "Mandy was amazed, he's excited now.

It's one thing to see it on TV, it's another thing to experience it firsthand, especially when you're a powerful witness to the Ox Harbor Trevally.

Bi Fang went down with a few spears, and the blood of the Niugang trevally gushed out of those holes.

"Cow trevally is rarely bought, not only because the meat is not good, but also because it has a lot of toxins in its body."

"This guy mainly feeds on crustaceans, arthropods, fish and water birds, and some of the crabs, shrimps, snails and marine fish it likes to eat contain natural biotoxins that will accumulate in the blood of the cow harbor trevally, so it can be quickly bloodied and detoxified after being caught to prevent accidents after eating."

This is a point that only some veterans of sea fishing know, and many novices don't even know anything about it, and even amateurs like Keko don't know that there is such a thing.

It's no wonder that the last time I went out fishing, I saw someone piercing a few holes in the trevally that he had caught, and at that time Keko thought he was tired and was angry with it.

Bi Fang and Keko dragged the 70-kilogram Ox Harbor Trevally to the shore.

"Eat, you're going to eat it?"

Bi Fang nodded: "I want to taste it." ”

Although it is not delicious, it is all Bi Fang knows, he has never tasted it himself, let alone caught it himself, there is no need to throw it away in vain.

"How the hell did you kill it?" Mandy and Keko were curious.

Bi Fang shook his head again and told the two of them the scene that had just been underwater.

Mandy's eyes lit up, clearly excited to meet her kind.

"I hope that the last blow will dispel the dolphins' good feelings for people, and it is better to run far away, and leave when you see the fishing boat, and never return here." Bi Fang sighed.

The atmosphere fell silent abruptly.

Keko nodded silently, in order to prevent dolphins from having a good impression of humans, isn't this a kind of sadness?

"Okay, don't overthink it." Bi Fang pressed the shoulders of the two of them and looked up at the moon in the sky, "It should be around twelve o'clock now, we don't have much time, hurry up and get to work!" ”

"We did all this early and told the public all the truth, that's what we're here for!"

The black bear hunting season began on July 12, and on the first night, Bi Fang, Mandy, Keko, and the three of them set up a part of the camera in the jungle.

Today is the second day of the hunting season, that is, the night of the thirteenth, and I will try to set up all the underwater cameras in one night.

There are still many places on the mountain that are good angles for shooting, and I haven't had time to install them.

In order to bring these equipment, Richard and the others shared a total of forty-three large boxes, which shows how heavy the task of the three Bi Fang is.

This is not just a matter of moving things out and discharging them, but placing them in the right place and at the right angle according to different assumptions and camouflage.

According to the information heard from local fishermen on the first night, the dolphin fishing season will take place on July 15, that is, the evening of the day after tomorrow.

In the evening, a grand festival is held to announce the beginning of the annual dolphin fishing season, which lasts for more than half a year, and on the morning of July 16, a large number of fishing boats will sail out of the harbor and use sonar devices to drive all the dolphins from the nearby waters to the dolphin bay, which is surrounded by mountains on three sides.

Carry out group pit killings.

There is not much time left for them, tonight, the night of the fourteenth, quite a little more and one more night of the fifteenth, and there are three more chances for the slaughter to begin.

Time waits for no man.

The three of them acted quickly, and Mandy nervously changed into a spare diving bottle and followed Bi Fang into the water.

Ten meters, twenty meters, thirty meters.

Bi Fang and Mandy quickly adapted to the process and dived deeper.

After more than 30 meters, a completely different feeling arose.

The whole body is different, and the huge pressure of the sea water will slowly change the density of the two people's bodies, when they reach a certain critical point.

Bi Fang felt that his body sank, and the buoyancy could no longer completely counteract the gravity, and under the drag of gravity, the two slowly fell towards the depths.

It's a touch that a diving trainer can't bring at all, magical and wonderful.

They are slowly pushed into the depths of the ocean.

There are three most important laws of diving that any diver needs to keep in mind, and they are:

Boyle's Law.

Dalton's Law.

Henry's Law.

Sounds familiar, huh?

That's right, these are the three laws of gas.

The vast majority of recreational divers use air or enriched air as their primary breathing gas, and these scuba diving gas laws apply to all breathing gases, and in many other areas of diving, such as Bifang and Mandy's technical diving, trimix or pure oxygen may be encountered.

The first iron rule of scuba diving: never hold your breath!

Corresponds to Boyle's law: for an ideal gas, the pressure is inversely proportional to the volume when the temperature is constant.

Think of the lungs as a balloon where we can inhale and blow it up, or exhale to empty the air inside it and shrink it.

When we dive, the pressure rises, and with each breath, the air inside the lungs is compressed, but the space in the lungs is filled up again when we breathe in a full breath.

The deeper you dive, the higher the pressure, and the more air you need to fill it, so the air consumption increases.

The pressure on a diver's lungs at great depth causes them to need more energy to expand their lungs.

When breathed regularly, the "balloon" never inflats too much.

The same is true of the two laws that followed.

Deep diving is called technical diving because there are so many technical means contained in it.

It's a balancing of lungs and qi.

Coincidentally, Bi Fang knows this well.

These abyssal worlds, as if completely cut off from the rest of the earth, have been waiting there for millions of years until Bi Fang's flashlight casts the first rays there.

Forty meters away, an anti-pressure infrared detector was installed.

This is a military equipment, under normal circumstances, it cannot be taken out of the country at all, it is approved after the Bi side makes an application, through infrared, can better detect the activities of dolphins.

Above thirty meters, the sun can barely shine, and below thirty meters, even during the day, it will be pitch black here, so further down, Bi Fang and the others need to install no longer cameras, but detection devices.

Most of these devices may be useless, but they must exist, just as there will be a lot of discarded footage in a movie shoot, not every device can shoot just the right shot, but it must exist.

After loading, Bi Fang did not venture down, turned on a flashlight, and made a series of flash signals at Mandy.

When Mandy finished answering, he also flashed out, and Bi Fang answered.

After confirming that the two of them were fine, Bi Fang adjusted the gas in the oxygen cylinder and continued to dive.

Diving to a depth of 40 meters is often defined as recreational diving.

Why did you choose the number 40 meters?

Two reasons.

One, diving at this depth, you can directly rise to the surface in an emergency without worrying about serious safety issues.

Second, the partial pressure of air at sea level is one bar, then under the partial pressure of oxygen of 1.4 bar, the toxicity of oxygen will become more and more great, and oxygen poisoning may affect the central nervous system of divers, causing underwater nerve convulsions in divers.

This directly affects the diver's ability to bite the regulator.

Similarly, when the partial pressure of nitrogen is about 30 meters and exceeds about 3 bar, some divers will feel anesthetic, and this feeling will increase as the partial pressure increases.

This is Henry's Law, which deals with the solubility of a gas in a liquid as a function of the surrounding pressure.

As the depth of the dive increases, so does the accumulation of nitrogen in the human body.

This nitrogen gas causes the body to enter a state similar to drunkenness, commonly known as "nitrogen drunkenness".

At depths below 40 meters, the effects of nitrogen intoxication can be so strong that people lose their ability to judge and react, which can lead to safety accidents.

Many people don't even realize that they are drunk, they feel very sober and even high, but they can't even do the basic math problem of one plus one equals two.

Just now, Bi Fang and Mandy were confirming each other's sobriety, and gave each other a two-digit addition and subtraction math problem.

For this reason, the depth limit of recreational diving has been set at 40 meters, and diving beyond 40 meters enters the field of technical and industrial diving.

Decompression sickness and nitrogen intoxication are all caused by nitrogen, but it is not possible without nitrogen, because direct inhalation of pure oxygen is toxic.

Astronauts can breathe pure oxygen for a few hours before a spacewalk and will not be affected by decompression sickness, but this is because the air pressure inside the spacesuit is smaller than that inside the space station, which is equivalent to a decompression environment.

Pure oxygen toxicity is conditional—when the partial pressure of inhaled oxygen exceeds 0.3 bar (30 kPa), oxygen becomes toxic to cells.

What space astronauts can do, they can't do underwater, and inhaling pure oxygen in an underwater high-pressure environment can lead to oxygen poisoning.

The human body is so fragile.

To be even more accurate, at depths of more than 55 meters, even breathing air can cause oxygen poisoning, let alone breathing pure oxygen.

At this time, the oxygen cylinders behind Bi Fang and Mandy both had three gases, helium, oxygen, and nitrogen.

This is the so-called three-phase gas, the addition of helium, so that the content of oxygen and nitrogen are reduced, just how to mix the content, is enough to give amateurs a headache.

Not only is this the case with diving, but it is also more troublesome to ascend, and you need to stay at different depths for enough time to gradually expel excess nitrogen from your body.

The world record for technical diving was set in 2014 by a man named Ahmed Gabr, who dived to a depth of 332 meters.

It took only 14 minutes for Gabr to descend to 332 meters, but it took 14 hours to rise to the surface.

Even if Bi Fang can now enter the realm of 70 meters at once by diving with his bare hands, this is all based on the fact that he does not need to stay for a long time, and the changes in his body are not too drastic.

If he stays too long, he also needs to obey the laws of physics.

50 meters underwater.

Bi Fang's body enters the second stage, and the capillaries in the lungs begin to congest and harden to protect the chest cavity from water pressure.

The pressure is getting bigger and bigger, and ordinary people who don't make any preparations, and who instantly enter such a stressful environment, will definitely die.

A long time passed, up to 80 meters underwater.

Eighty meters, a figure that makes people feel suffocated, but the more they struggle, the more dangerous it becomes.

Here, you can only rely on mental and psychological strength to overcome, tell yourself that you can go with nature, and only by completely relaxing, can you turn harm into protection.

In the dark world, far away from light and human beings, accompanied only by coldness and loneliness, Bi Fang seemed to become a small droplet, floating quietly in the ocean.

With the last piece of equipment installed, both Mandy and Bi Fang breathed a sigh of relief.

Plan complete!

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