The U.S. Coast Guard announced via Twitter early Thursday that a remotely operated vehicle (ROV) deployed by the Canadian vessel Horizon Arctic has reached the sea floor, beginning its search for the missing submersible.

Meanwhile, the French vessel L'Atalante is preparing its ROV to enter the water in the search area, the U.S. Coast Guard said.

Time is running out as rescuers race to locate and save five people trapped in a submersible that vanished during a tour of the Titanic wreckage on Sunday morning.

The deep-sea vessel submerged at 8 a.m. ET on Sunday with a 96-hour oxygen supply, according to the U.S. Coast Guard. That amount of breathable air is forecast to run out on Thursday morning.

The search and rescue mission remains ongoing.

The New York Times traced the lineage of Wendy Rush, wife of missing OceanGate CEO Stockton Rush, and found that she's the great-great-granddaughter of a couple who died on the Titanic, Isidor and Ida Straus.

The executive director of the Straus Historical Society told ABC News that The Times article, which cites archival records, is largely correct with regard to Wendy Weil Rush's heritage.

-ABC News' Nic Uff

A U.S. Navy portable crane system capable of bringing up items from as deep as 20,000 feet has arrived in St. John's, Newfoundland, but is waiting to be welded onto a chartered ship to take it to the search area for the missing submersible, according to a U.S. Navy official.

The Navy has not yet contracted a ship for the salvage system, known as Fly Away Deep Ocean Salvage System or FADOSS, the official told reporters Wednesday. Once the ship is contracted, Navy teams will spend approximately 24 hours working around the clock to weld the system aboard the ship before it can leave port, the official said.

FADOSS is the salvage system the U.S. Navy uses for all of its deep-water recoveries. Last year, it was able to bring up an F/A-18 aircraft that had fallen into the waters of the Mediterranean Sea.

-ABC News' Luis Martinez

The U.S. Navy said it's sending to the search site experts and equipment "designed to provide reliable deep ocean lifting capacity for the recovery of large, bulky, and heavy undersea objects."

The equipment, which can lift up to 60,000 pounds, and the experts will arrive in Canada Tuesday night, the Navy said.

National Security Council spokesperson John Kirby said earlier Tuesday that the Navy was"on standby" to help with the search for the missing submersible, because the Navy has "some deep-water capabilities that the Coast Guard wouldn’t necessarily have."

President Joe Biden is "watching events closely," Kirby said, adding that Biden and the White House offer their thoughts "to the crew onboard, as well as to the -- what is no doubt -- worried family members back on shore."