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.

The co-founder and Board chair of Horizon Maritime, the company that owns the Polar Prince boat that took the Titan submersible out to sea, is speaking out.

"We have been supporting the Titanic expeditions for several years," Sean Leet said, calling the Polar Prince "an iconic former Canadian Coast Guard icebreaker that has been upgraded with advanced technology."

"All protocols were followed" for the submersible's mission, he said at a news conference Wednesday, calling the missing sub an "unprecedented" situation.

Equipment heading to search site can reach the depths of the submersible and potentially take it to the surface, he said.

"We wish to thank everyone involved in this rescue mission, especially the U.S. and Canadian Coast Guards, the organizations that have made their marina assets available including the French government … [and] the many private companies that have dropped everything at a moment's notice," Leet said.

"Our thoughts and focus remain with the crew of the Titan and their families," he said.

Leet said he is holding out hope that the five-person crew will be brought home safely.

"We'll continue to hold out hope until the very end," he said.