What is a 'catastrophic implosion'? Pressure but no pain likely marked the end for Titanic sub

For days, the world could only imagine the grim scene: five men cramped in a cold, dark tube, knowing that they were about to run out of air. In reality, those aboard the Titan submersible most likely died instantaneously in what officials called a "catastrophic implosion."

The deep-sea water pressure that appears to have crushed the 22-foot craft would have been roughly equivalent in weight to the 10,000-ton, wrought-iron Eiffel Tower, experts told NBC News on Friday. The colossal forces would have acted so quickly that it would be like the vehicle’s carbon-fiber hull “suddenly vanishing” before anyone inside knew what was happening, one expert said.

“They would have known nothing — the minute this body of water hit them, they would have been dead,” said Paul White, a professor at England’s University of Southampton, who specializes in underwater acoustics and forces.

With the vast search effort now over, the focus turns to the many unanswered questions that remain.