What are the dangers of a submarine diving below 1000 meters?

Diving below 1,000 meters poses several dangers for submarines, primarily due to extreme pressure, which can compromise the vessel's structural integrity. The risk of hull failure increases significantly, potentially leading to catastrophic implosion. Additionally, the deep-sea environment presents challenges such as limited visibility, increased thermal gradients, and potential encounters with underwater topography, which can complicate navigation and operations. Furthermore, communication and rescue capabilities diminish at such depths, making emergency situations more perilous.