Titanic submersible: What a 'catastrophic implosion' means and what officials found

A submersible carrying five people while on a trip to the Titanic wreckage suffered a "catastrophic implosion," U.S. Coast Guard Rear Adm. John Mauger said at a press conference on Thursday.

A remote-operated vehicle found debris from the OceanGate Titan submersible's tail-cone approximately 1,600 feet from the ship, Mauger said.

A search and rescue team found several additional pieces of debris that indicated they belonged to the Titan, the missing vessel that drew international attention in recent days, Mauger said.

It remains "too early to tell" when the implosion took place, but the search and rescue team will continue to collect information, Mauger added.

"This is an incredibly unforgiving environment on the seafloor," Mauger said. "This is something that happened in a remote portion of the ocean."

In a statement, OceanGate confirmed the deaths of all five passengers on board.

"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans," the company said. "Our hearts are with these five souls and every member of their families during this tragic time."

What type of debris did the search and rescue effort find?

The search and rescue team identified two fields of debris in an area surrounding the bow of the sunken Titanic, Mauger said, describing them as one large field of debris and one small field.

The discovered objects included "five different major pieces of debris" that identified the materials as consistent with the Titan, undersea expert Paul Hankin said at the press conference.

The debris included a nose cone and one end of the pressure hull, Hankin said.

"We've continued to map the debris field," Hankin said. "We'll do the best we can to fully map it out."

What does "catastrophic implosion" mean?

Titan is a carbon fiber submersible that can travel as far as 4,000 meters below sea level, the OceanGate website says.

At the depth of the Titanic, which sits 3,800 meters below sea level, the pressure reaches a level 380 times the atmospheric pressure on the Earth's surface, Stefan Williams, a professor of marine robotics at the University of Sydney, said in a blog post on Tuesday.

A fault or failure in the hull of the Titan could have led to an implosion, as the vessel gave way to the high pressure of the deep sea, Williams said.

The implosion of a submersible delivers immense force, oceanographer Bob Ballard told ABC News on Thursday.

"I don't think people can appreciate the amazing energy involved in the destructive process of an implosion," Ballard said. "It just takes out and literally shreds everything."

"It's extremely powerful," he added.

Are there previous examples of a submersible imploding?

A U.S. nuclear submarine, called Thresher, imploded during a deep-sea dive 220 miles off the coast of Cape Cod, Massachusetts, a U.S. Navy inquiry showed.

The implosion left 129 sailors dead.

More recently, in 2014, the unmanned Nereus submersible suffered a "catastrophic implosion" while traveling at a depth of 9,990 meters in the Kermadec Trench northeast of New Zealand, the Woods Hole Oceanographic Institution said soon afterward in a statement.

At the time of implosion, Nereus faced pressure of an estimated 6,000 pounds per square inch, WHOI said.

The team of researchers tracking Nereus found "spotted pieces of debris floating on the sea surface" that were later identified as part of the submersible, WHOI said.

Researchers lost contact with Nereus seven hours into a nine-hour mission, WHOI added.