A Royal Canadian Navy ship HMCS Glace Bay has been on scene since about 8 a.m. ET Thursday morning. The ship provides a medical team specializing in dive medicine and a six-person mobile hyperbaric recompression chamber, according to officials.

Canadian Coast Guard ships John Cabot, Ann Harvey and Terry Fox are on scene and ready to provide rescue equipment and personnel should assistance be required. A Royal Canadian Air Force CP-140 Aurora aircraft is also maintaining continuous on-scene support with additional aircrews and assets, according to officials.

-ABC News' Luke Barr

The U.S. Coast Guard announced via Twitter late Thursday morning that "a debris field was discovered within the search area by" a remotely operated vehicle (ROV) "near the Titanic" wreckage.

"Experts within the unified command are evaluating the information," the U.S. Coast Guard tweeted.

The Coast Guard is set to hold a briefing on the findings from the Horizon Arctic's ROV at 3 p.m. ET.

Despite their onboard oxygen tank expected to be depleted sometime Thursday morning, one doctor says they may have more time if the passengers are still alive. He estimates the five people aboard the lost Titanic tourist sub could survive for 10 to 20 hours with air still circulating through the experimental capsule.

Dr. Richard Moon, a professor of anesthesiology at Duke University, said that despite conditions being dire, those aboard the OceanGate Expedition's submersible could extend the oxygen available after its tank is depleted by staying calm and moving as little as possible.

"The actual amount of time that they have is unpredictable, but it's probably less than 24 hours after the final oxygen in the tank is depleted," Moon, director of the Duke Center for Hyperbaric Medicine and Environmental Physiology, told ABC News.

Read more here.

-ABC News' Bill Hutchinson

The U.S. Coast Guard announced via Twitter on Thursday morning that a remotely operated vehicle (ROV) deployed by the French vessel L'Atalante has entered the water in the search area.

The U.S. Coast Guard also gave an update on the conditions at sea, saying winds were at 14 mph with gusts up to 19 mph, swells were 4 to 5 feet and the air temperature was 50 degrees Fahrenheit.

OceanGate co-founder Guillermo Söhnlein is coming to the defense of late CEO Stockton Rush, one of those killed in the implosion of Titan, after criticism from director James Cameron, and others, who said the sub's carbon-fiber hull was dangerous.

"In this kind of community, there are completely different opinions and views about how to do things, how to design submersibles, how to engineer them, build them, how to operate in the dives," Söhnlein told the U.K.'s Times Radio on Friday. "But one thing that’s true of me and the other experts, is none of us were involved in the design, engineering, building, testing or even diving of the subs. So it’s impossible for anyone to really speculate from the outside."

Söhnlein co-founded OceanGate in 2009 with Rush and led several dives in the early days of the company. He left OceanGate in 2013, when Rush took over as CEO, but maintained a friendship and spoke to Rush just weeks before the doomed expedition, he said on Facebook.

Cameron, who not only directed the Oscar-winning film "Titanic" but is a prolific ocean explorer, criticized the use of a carbon-fiber hull in the construction of Titan, saying it was only a matter of time before it cracked under the pressure from repeated dives. Rush, in the past, defended its use, saying it had a better strength-to-buoyancy ratio than titanium.

"I was involved in the early phases of the overall development program during our predecessor subs to Titan, and I know from firsthand experience that we were extremely committed to safety and risk mitigation was a key part of the company culture," Söhnlein told Times Radio Friday.