Can pressure destroy a submarine underwater?

All submarines have a rated "Crush Depth", the depth at which the hull will succumb to external sea pressure.

While the actual depths for each class are classified, several submarines were lost during the Cold War to implosion events after major casualties. The most noted for the United States was the USS Thresher (SSN-593) which was lost during sea trials after she suffered a major flooding casualty. It was estimated she made it to within 100' of the surface before sinking to her crush depth and the bottom of the ocean.