The Titan had made more than two dozen deep-sea dives, which put repeated stress on the hull, said Jasper Graham-Jones, an associate professor of mechanical and marine engineering at the University of Plymouth in the United Kingdom.

That stress could potentially cause delamination, a horizontal splitting of the carbon-fiber hull, he said.

A similar disaster occurred in 1963 when the USS Thresher, a nuclear-powered submarine, likely imploded when it exceeded "test depth” after a series of other failures. Killed were 129 sailors and civilians on a routine test dive off Cape Cod.

Associated PRESS