"crush the hull" . "submarine depth rating" . "operational diving depth" . "Calculated crush depth" . "depth ratings" . "depth advantage" . "Crush depth" . . "design depth rating" . "Test depth" . "crush depth" . "safe diving depth" . "Submarine depth ratings" . . "Submarine depth ratings" . . "submarine's rated limit" . . "depth reaching" . "Submarine depth ratings#Crush depth" . "hull-crush depth" . "collapse depth" . "maximum safe depth" . "diving depth" . "test depth" . "maximum depth" . "dive depth" .