Why are submarines most afraid of encountering cliffs at the bottom of the sea?

Submarine cliffs are the nightmare of submarine. The so-called submarine cliff does not really break like a cliff, but there is a great density difference between the upper and lower layers. The density of the upper layer is much higher than that of the lower layer. The huge pressure caused by the density difference will cause the submarine to fall, and it can't float up by conventional drainage, just like falling into a cliff. When the descent depth exceeds the limit depth of the submarine, the consequences can be imagined. In the history of the global navy, there have been more than one tragedy caused by submarine falling off a cliff.

Navy submarines dive underwater, which is the normal navigation state of submarines. However, due to the weather, the distribution of salt in tropical and subtropical waters is uneven, and the buoyancy is high and low, forming an underwater cliff. The submarine traveling at a constant speed sailed under 200 meters, and the tank counterweight was blown up. Suddenly, the salt concentration in the water ahead dropped sharply, and the submarine suddenly lost its buoyancy and sank into the deep sea.

If the submarine sinks sharply and can't be controlled, when the submarine moves below the safe depth, the huge seawater pressure will crush the pressure hull of the submarine and bring disaster to the submarine. Therefore, "falling deep" is listed as the first danger that submarines are most afraid of and most difficult to deal with.

For submarines, the reaction time is very short, and submarines should immediately drain water to increase buoyancy. After a series of operations, it is possible to drop hundreds of meters. Once it exceeds the safe diving depth, it will be fatal, causing the hull to be crushed by tremendous pressure and there is no possibility of being rescued. Since World War II, there have been several submarine crashes in navies of various countries, but China's 327 submarine has successfully escaped this disaster, which has to be said to be a miracle and legend.