Deep Sea Subs

No.11000646 ViewReplyOriginalReport
Why are military submarines only able to dive to relatively shallow depths? Pic related is the deepest diving military sub and can only go to about 3000 ft under water.

The average Ocean is over 3 times that much at ~12,100 ft or a little over 3 kilometers. The strategic advantages of a deep sea sub would be huge and sonar is very ineffective at abyssal depths which the world's ocean floors are predominately made of.

Think about it, a sub that could sit on the abyssal floor could save power, have a more stable firing platform, be out of range of sonar or torpedos and could fire up at targets who would have little to no warning of them.

If the ALVIN submersible can dive so deep why can't a military sub? What challenges are faced in designing something like this?