Today marked the final day of testimony in the U.S. Coast Guard hearing investigating last year's loss of the OceanGate Titan submersible.

For the final day of a top-level Coast Guard investigation into why an experimental submersible catastrophically failed diving to the Titanic wreck site, witnesses have dived into the search and rescue operations that began when the Titan sub lost contact with its support vessel the Polar Prince.

The Coast Guard's Marine Board of Investigation heard from more than two dozen witnesses, including several former employees of OceanGate.

Contrary to public reports last year, the passengers probably had no idea that the vessel was about to implode.

Over two weeks of testimony, witnesses in a U.S. Coast Guard hearing described safety concerns surrounding an experimental deep-water submersible that imploded, killing five people last year.

To begin the seventh day of a Coast Guard inquiry into why a submersible imploded, killing all five of its passengers, a National Transportation Safety Board