An aerial view shows the research vessel Deep Energy, one of the ships searching for the Titan submersible in the North Atlantic Ocean. (U.S. Coast Guard Photo)

[Update, Thursday, June 22: OceanGate submersible and crew declared lost after discovery of debris near Titanic]

Searchers are continuing to hear what they describe as “banging” noises as they monitor underwater sounds for signs of an OceanGate submersible that went missing during a dive to the wreck of the Titanic.

A growing fleet of remotely operated vehicles is focusing on areas of the North Atlantic Ocean where the sounds appear to be coming from, but so far, no signs of the sub have turned up, said U.S. Coast Guard Capt. Jamie Frederick, a spokesman for the international search team.

“We’re searching where the noises are, and that’s all we can do,” he said today at a news briefing.

The five-person Titan submersible, built by Everett, Wash.-based OceanGate, went out of contact about an hour and 45 minutes into what was expected to be an hours-long dive on Sunday. Five crew members, including OceanGate CEO Stockton Rush, were due to head down more than 12,500 feet to survey the world’s best-known shipwreck and the surrounding seafloor.

The journey was part of OceanGate Expeditions’ campaign to document the deterioration of the wreck — a series of annual expeditions that began in 2021. In addition to Rush, the crew includes veteran Titanic diver PH Nargeolet and three mission specialists who paid a fare listed at $250,000 to participate in the adventure.

One of the mission specialists is Hamish Harding, a British aviation executive who bought a ride on Blue Origin’s suborbital spaceship last year. The other two are Pakistani business executive Shahzada Dawood and his son, Suleman.

When OceanGate and its maritime partners were no longer able to hear from the submersible on Sunday, they alerted U.S. and Canadian authorities — and the search began with aerial surveys on Monday.

OceanGate says the Titan sub is designed to provide life support for up to 96 hours, a length of time that runs out on Thursday. However, Frederick said searchers were not fixated on the clock, and would keep trying to retrieve the submersible even if the operation didn’t locate the sub by Thursday. “When you’re in the middle of a search-and-rescue case, you always have hope,” he said.

He said a Canadian P-8 Poseidon plane equipped with sensors capable of detecting underwater sounds heard noises repeatedly on Tuesday and this morning. However, he couldn’t confirm reports that the noises were repeated every 30 minutes — and he said experts haven’t yet characterized the sounds.

“We don’t know what they are,” he said.

Carl Hartsfield, who heads up the Oceanographic Systems Lab at the Woods Hole Oceanographic Institution, said it’s not always easy to determine the cause of sounds heard at sea.

“There are sounds by biologics that sound man-made to the untrained ear,” he said. “But I can assure you that the people listening to these tapes are trained. There are a lot of vessels in the area, and they each make noise, right? So all that has to be eliminated, and it’s analysis over time.”

Frederick said aerial searchers spotted an object floating on the sea surface around the area where the submersible made its descent, “but they now believe that the object is not related to the missing submarine.”

The search-and-rescue armada is continuing to grow, and spreading out over an area that’s now twice the size of the state of Connecticut, Frederick said. Searchers are coping with winds gusting up to 30 mph, sea swells that range up to 6 or 7 feet, and occasionally foggy conditions.

“We currently have five surface assets searching for the Titan, and we expect 10 total surface assets to search in the next 24 to 48 hours,” Frederick said. “There are two ROVs actively searching, and several more are en route and will arrive by tomorrow morning. We’ve received incredible support with aviation assets from our Coast Guard air station in Elizabeth City [in North Carolina], the Air National Guard and Canadian Armed Forces.”

Frederick said a French team was due to bring in “state-of-the-art” equipment, including an ROV with capabilities that surpass what would be needed to get to the wreck of the Titanic.

“Once they get on, we’re going to have more assets to look, and we’ll continue to put them where we think the best location is,” he said.

Like what you're reading? Subscribe to GeekWire's free newsletters to catch every headline

Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.