Deep in the Pacific Ocean, in the dark waters, a great silent shadow slowly walked.

This is a strategic missile submarine belonging to the Chinese side, which has been away from Hong Kong for more than two months and has been diving in the depths of the ocean. The submariners are isolated from the world, like everything in the world has nothing to do with them.

The sonar soldier had a large headset on his head, and he stared at the monotonous waveform on the screen without a glance, and he could see his eyelids fighting violently.

Half-asleep and half-awake, a faint noise was suddenly heard in his ears, and the sonar soldier bounced up like an electric shock, widening his eyes and listening intently.

The noise is very weak, but it is clear, and various information about the sound source is given on the screen.

"What's the situation?" The captain discovers the sonar man's anomaly.

"Report, an unknown sound source was found, the port side was 22 degrees, the distance was 62 kilometers, and the target movement echo was stable...... As if it were a nuclear submarine of the Americans. The sonarman's voice became smaller and quieter as he spoke.

The captain raised his eyebrows: "62 kilometers, what are you talking to me?" ”

There are many factors that affect the effective distance of sonar, the most important factor is the hydrological conditions and the intensity of the sound source, if the noise of the sound source is lower than the ocean background, the passive sonar of the submarine can also listen to more than 20 kilometers, and the active sonar is about 40 kilometers.

Not to mention that the active sonar on the boat is not turned on, even if it is turned on, the noise from more than 70 kilometers away cannot be heard, what if it is a towed base array?

The sonar soldier called a grievance: "It's really 72 kilometers...... There is another one, 19 degrees on the starboard side and a distance of 54 km...... Captain, this one knows better than the one just now! ”

"How is that possible?" The captain took the headset and put it on his head, and sure enough, he heard a clear noise, and he couldn't help but be stunned.

The sonar soldier whispered, "Probably full speed ahead." ”

"You say it!" The captain glared at the sonar soldiers, but he couldn't understand why the two submarines suddenly went crazy.

"Report!" The signal corpsman suddenly shouted, "Headquarters order: South, full speed." ”

The captain frowned: "What kind of thing is headless and brainless?" ”

"I haven't received the rest yet." Said the communications soldier.

Submarines in the depths of the ocean can only receive long-wave communications, and the long-wave frequency is low, the amount of information carried is small, and it takes less than half an hour to receive a telegram.

Without hesitation, the captain ordered: "Adjust the direction immediately, to the south, full speed!" ”

At the sound of an order, the submarine hidden in the depths of the ocean turned south at a maximum speed of thirty knots per hour.

Generally speaking, the headquarters should give the submarine a signal, and after the submarine floats, it uses a high-frequency radio to exchange data with the headquarters, but today is different from the past, and there is no signal at all.

During the voyage, the submarine continued to receive messages from the headquarters, and gradually pieced together the truth of the incident.

It was only at this time that the captain knew the news of the alien landing from Antarctica, and finally understood why the headquarters did not give the signal to float - the surface speed of the submarine is only twenty-four knots, and it must be submerged to reach thirty knots, and the reason why it does not float is to grab the speed of these six knots!

Not only did the submarines in the depths of the ocean receive the order, but the various submarine bases also received the order to sail at the first time, except for those that were on the slipway and couldn't move, the rest was counted as one, and all the submarines that could be launched were desperately running to the South Pole.

It is not only submarines but also aircraft carriers, amphibious landing ships, destroyers, and frigates...... As long as all the naval vessels capable of anti-submarine warfare are out on sail and all kinds of antisubmarine equipment are on the battlefield, an invisible net is gradually taking shape.

The navy never imagined that the surface fleet would also have a day against the alien fleet, which is really emotional.

However, the first to intervene were the satellites in the sky, which used a pair of sharp electronic eyes to see through the ocean, looking for traces of alien warships.

In the beginning, satellites did find a lot of alien warships, but as time went on, more and more alien warships disappeared into the depths of the ocean.

Satellites can only detect targets on the surface and in shallow seas, and once the target dives into the dark deep sea, the satellite loses its target.

All in all, all human countries have done their best to find out the alien warships that have infiltrated the ocean.

The first to arrive near the South Pole was a U.S. destroyer, which immediately released towed sonar to listen for unusual noises underwater.

This thing can reach a listening range of hundreds of kilometers, which is much more effective than submarine sonar, but the alien battleship did not find it, but first turned over a few submarines that were on their way at full speed...... The noise they make is just too loud.

Submarine noise is nothing, and what's even more tricky is that no one knows the noise signature of an alien warship!

There are so many strange sounds in the ocean, and when the sonar is working normally, it filters out the messy sounds first, and only listens for suspicious sounds.

But without a noise signature, the filter becomes an ornament, and the sound that most likely belongs to an alien warship must be picked out from the cluttered ocean background.

This matter is not easy to say, and it is not difficult to say, but fortunately, the navy has no shortage of talents in this area.

The process of forming a space fleet is very similar in various countries, and they have all withdrawn too many talents from the navy, but the space fleet only uses radar and does not use sonar, so most of the talents in sonar remain in the navy.

Moreover, countries are not blindly searching, but also input the shape of alien warships into supercomputers, and use supercomputers to calculate what kind of noise alien warships will produce when they sail in the water, so as to provide a basis for fleets to search for enemy ships.

However, the towed array found nothing, and the captain realized that he had fallen into a mistake and used the usual anti-submarine procedures on alien warships.

Realizing this, he immediately changed his tactics, retracted the towed sonar, and turned on the active sonar to find the enemy.

A loud slap spread far underwater, and all sorts of echoes filled the sonarman's ear drums, but nothing useful was heard.

The captain believes that such a large alien spacecraft does not conform to hydrodynamics, and the noise produced must be very obvious, but now there is no discovery at all, either the enemy ship has not yet entered this sea area, or the enemy ship is sitting on the bottom of the sea, and the sonar does not work at all.

The top brass of the US military very much agreed with this opinion and immediately took corresponding action.

Later, an air defense ship entered the search sea area and released twelve "torpedoes" under water.

This is a submersible robot that can work on the ocean floor for four to six hours all year round, and is the most suitable equipment for searching enemy ships if the alien warship does sink to the bottom of the sea.

Not long after the robot was launched, the sonar suddenly discovered that there was a group of special targets that were very fast and in the same direction underwater.

They rise from the bottom of the ocean at extremely high speeds and quickly approach the surface.