The United States Coast Guard has confirmed that debris belonging to the Titan submersible has been found near the wreck of the Titanic and all five passengers aboard the vessel are dead.
Rear Adm. John Mauger says a tail cone of the submersible and other debris from the vessel were found about 1,600 feet from the bow of the famous shipwreck.
Mauger says the debris was consistent with the catastrophic loss of the craft's pressure chamber.
He says the coast guard immediately notified the families of the five people aboard the submersible.
The submersible Titan, operated by U.S.-based OceanGate Expeditions, lost contact with surface vessels on Sunday morning as it was nearing the Titanic shipwreck during a 3,800-metre dive.
The debris was discovered by a crew operating a remotely operated vehicle aboard the Horizon Arctic, a Canadian-flagged offshore tug and supply vessel.
On Tuesday, a Canadian aircraft picked up "underwater noises" from one area of the search. Officials quickly supplied the area with teams in hopes of finding the location of the submersible.
More sounds were heard on Wednesday but officials could not determine if they were coming from the submersible.
Following the leads, officials have supplied the area where the noises were heard with ROVs from Canadian vessel Horizon Arctic and French ship L'Atalante.
The ships join the Canadian CGS Ann Harvey, Canadian CGS Terry Fox, His Majesty's Canadian Ship Glace Bay, which carry a mobile decompression chamber and medical personnel, and an ROV from Magellan, a press release from the U.S. Coast Guard said.
An Air National Guard C-130 and Canadian Royal Air Force (RCAF) planes are also on scene.
On Thursday, co-founder of OceanGate Guillermo Sohnlein wrote on Facebook, "today will be a critical day."
"I'm certain that Stockton (Rush) and the rest of the crew realized days ago that the best thing they can do to ensure their rescue is to extend the limits of those (oxygen) supplies by relaxing as much as possible," Sohnlein said. "I firmly believe that the time window available for their rescue is longer than what most people think."
Officials said Wednesday that efforts to find the submersible would scale up hour-by-hour overnight into Thursday morning.
The submersible was headed to the site of the 1912 sinking of the Titanic, located approximately 600 kilometres off the coast of Newfoundland at a depth of about 3,800 metres.
The crew aboard the support ship, the Polar Prince, lost contact with the submersible on Sunday an hour and 45 minutes into its dive.
OceanGate Expeditions, has been running tours to the British ocean-liner since 2021. Since the disappearance, details have emerged from a 2018 engineering report alleging issues with the submersible's structure.